EDMONDSON, J.

¶ 1 This case involves a trial court's dismissal of an action based upon its determination that the action was not brought in the forum that was specified in the attorney-client written agreement. We hold that a party should utilize the 12 O.S. § 2012(B)(6)/summary judgment procedure when that party seeks to dismiss an Oklahoma proceeding based upon an alleged contractual right of interstate venue selection. The matter is remanded to the District Court for the parties to adjudicate their respective claims by the proper procedure.

I.

¶ 2 The City of Oklahoma City charged Christopher Tucker (Tucker) with municipal misdemeanor offenses of interfering with official process, obstructing an officer, and failing to obey lawful commands of an officer. On August 9, 2010, Tucker signed an agreement for the Cochran Firm-Criminal Defense, Birmingham, L.L.C., (Cochran Firm), to provide him with legal representation for his scheduled trial in October of 2010. Tucker was found guilty of a municipal charge as a result of the trial proceedings.

¶ 3 Tucker filed an action in the District Court of Oklahoma County against the Cochran Firm alleging that the Case Manager for the law firm, John Pride, had misrepresented the nature of the services that the law firm would provide and that the Cochran Firm had (1) committed actual and constructive fraud, (2) committed acts of legal malpractice and negligence, (3) violated the Oklahoma Consumer Protection Act (15 O.S. §§ 751-764.1), (4) committed the tort of outrage, and (5) breached the parties' agreement.

¶ 4 Tucker alleged that the Case Manager informed him that the law firm would engage in a four to five-day trial to defend Tucker, the law firm would provide an experienced trial lawyer with twenty to thirty years of experience to represent him at trial, and that the law firm "had attorneys who were licensed to practice in Oklahoma and who would in fact defend the Plaintiff in trial...." He alleged that these statements were untrue and were made to fraudulently induce him to enter into an agreement for legal services and to pay "outrageous fees." The law firm required Tucker to pay a non-refundable retainer of $13,690.00 for legal representation for the trial. Tucker had paid to the law firm $12,200.00 in installments by the time his trial occurred.

¶ 5 He also alleged that a few days after he signed the agreement, the Cochran Firm informed him that Josh McKeown, an attorney with the firm, would represent him at the trial. He further alleged that on the morning of his trial he met for the first time the attorney who actually represented him at his trial, an Oklahoma lawyer, E.W. Childers. Tucker alleged that during the trial McKeown was in the courtroom seated in the area for the public and "whispered a couple of times to Childers." He also alleged that the Cochran Firm paid Childers $500.00 to represent him at his trial which lasted approximately forty minutes.

¶ 6 Tucker alleged that McKeown had not sought to be admitted pro hac vice for the trial. He also alleged that the Cochran Firm had (1) failed to request a court reporter for preparation of a trial transcript for an appeal, (2) failed to conduct any discovery or otherwise request documents and evidence from the City of Oklahoma City, (3) failed to secure and subpoena the police vehicle videos and videos from nearby businesses, (4) failed to obtain information concerning complaints and disciplinary actions concerning the police officers involved, (5) failed to obtain character witnesses for Tucker, (6) failed to prepare witnesses for the trial, (7) failed to obtain an expert witness for Tucker as promised by the Cochran Firm, (8) failed to submit a trial brief on a specific issue, (9) failed to object to the identification of evidence, (10) failed to move to suppress evidence based on an officer's lack of probable cause or reasonable suspicion to stop, (11) failed to seek admission pro hac vice, and (12) failed to adequately prepare with local counsel.

¶ 7 The Cochran Firm filed a motion to dismiss Tucker's petition. The law firm's motion relied on 12 O.S. § 19;1 a forum-selection clause in the contract; and Bakhsh v. JACRRC Enterprises, Inc., 1995 OK CIV APP 40, 895 P.2d 746, where in an opinion released for publication by order of the Court of Civil Appeals, the court stated that parties to a contract may select the jurisdiction in which all actions arising from their transaction shall be heard, and a selected forum in Dallas, Texas, was held to be reasonable in the circumstances. The forum-selection clause at issue in this case states that: "This agreement shall be interpreted under the laws of the state of California and jurisdiction and venue shall be exclusively in the county of Los Angeles, in the state of California."2

¶ 8 This initial motion to dismiss was denied by the trial court because it was signed by an attorney not admitted to practice before the court. Lawyers for the Cochran Firm subsequently sought to vacate the trial court's ruling pursuant to 12 O.S. § 1031.1 with an argument that the person who signed the initial motion to dismiss was "a member" of the Cochran Firm acting as a "pro se defendant." The trial court vacated its order denying the motion to dismiss; directed the Cochran Firm to file an amended motion to dismiss; and ordered that the amended motion to dismiss, when filed, would relate back to the date the initial motion to dismiss was filed.

¶ 9 After filing the amended motion to dismiss, the trial court determined that the forum-selection clause in the retainer agreement should be judicially enforced. The trial court also determined that enforcement of the forum-selection clause would not be unfair or unreasonable under the circumstances. The trial court dismissed the action for improper venue.

¶ 10 Tucker appealed and the Court of Civil Appeals, in an opinion released for publication, reversed the trial court and remanded the cause for further proceedings. The appellate court concluded that the Retention Agreement specified who must sign the agreement on behalf of the law firm, and that this was not done. The court concluded that in the absence of a written retention agreement, the parties had an oral retention agreement, and that the trial court had failed to determine whether there existed a valid forum-selection agreement between the parties.3 The court appears to have concluded that a forum-selection clause would violate public policy if the clause required obligations created by a lawyer-client relationship in an Oklahoma legal proceeding to be governed by the law of another state.

¶ 11 The Cochran Firm filed a petition for certiorari in this Court and argued that (1) the appellate court should have applied an abuse-of-discretion standard instead of using a de novo review, (2) the burden of persuasion is on one attacking a forum-selection clause and the record shows that Tucker failed this burden, (3) a client-attorney fiduciary relationship does not apply when fees are negotiated, (4) the appellate court improperly adjudicated disputed questions of fact, and (5) the appellate court improperly based public policy considerations on allegations of fact where those facts occurred after the contract negotiation.

¶ 12 The Cochran Firm relies upon various opinions of the Court of Civil Appeals for the proposition that a forum-selection clause should be enforced and its argument on the nature of Tucker's burden in the trial court. Tucker relies on an opinion from the Court of Civil Appeals for the concept that a "reasonableness test" should be used when a court decides whether to enforce a forum-selection clause. Our Court of Civil Appeals has addressed whether forum-selection clauses in written agreements are enforceable in various circumstances.4 Although they constitute persuasive authority only and are not precedential because their publication was not pursuant to orders of the Supreme Court, they do serve as examples of courts in Oklahoma enforcing forum-selection clauses in Oklahoma since 1989.5 This Court has examined forum-selection clauses in the contexts of arbitration and issue preclusion,6 but the issues before us today have not been previously addressed by this Court.

¶ 13 Certiorari was previously granted by this Court, and we vacate the opinion of the Court of Civil Appeals. We have not previously addressed the procedure employed in the District Court and the respective burdens of the parties when a court adjudicates the enforcement of a forum-selection clause. We remand the case to the District Court for the purpose of providing the parties an opportunity to litigate the issue of the enforceability of the clause in this proceeding.

II.

¶ 14 The first issue raised on certiorari involves the allocation of the burdens of pleading, persuasion, and proof; and this necessarily raises the proper procedure for a party invoking a forum-selection clause. In the last twenty years, when a mandatory7 forum-selection clause specified an exclusive forum for both jurisdiction and venue8 the United States Court of Appeals for the Tenth Circuit allowed a defendant to judicially enforce that clause by a motion to dismiss for improper venue pursuant to Fed.R.Civ.P. 12(b)(3).9 On the other hand, the First Circuit Court of Appeals has treated a motion to dismiss based upon a forum-selection clause as a motion alleging the failure to state a claim for which relief can be granted pursuant to Fed.R.Civ.P. 12(b)(6).10 However, in its 2013 opinion in Atlantic Marine Construction Co. v. United States District Court for the Western District of Texas, the United States Supreme Court determined that the proper procedural method for enforcing a forum-selection clause in federal courts was through the doctrine of forum non conveniens and a statute allowing transfer of an action to another federal court.11

¶ 15 The Court indicated that federal venue provisions "alone define whether venue exists in a given forum" and a parties' agreement may not make venue improper in a forum where a federal venue statute makes venue proper.12 For this reason a Rule 12(b)(3) motion to dismiss for improper venue would not be available where venue was proper pursuant to federal statute even though the parties had previously agreed to a different forum: "... a forum-selection clause does not render venue in a court `wrong' or `improper' within the meaning of [28 U.S.C.] § 1406(a) or Rule 12(b)(3)...."13

¶ 16 Oklahoma's 12 O.S.2011 § 2012(B)(3) states that a motion to dismiss may be filed where "improper venue" is asserted.14 This Court, like the United States Supreme Court, has long-recognized that forum non conveniens does not present the issue of an "improper forum," but may apply when more than one forum is proper. We noted in Stevens v. Blevins that two proper venues must exist, and we explained that "this Court set forth procedural requirements including an application for a change of venue by the parties stating the facts on which the transfer is based ... [and] we found that an application for a change of venue under the doctrine of intrastate forum non conveniens must be filed by a party before the date fixed for filing an answer."15 The procedure was established by our opinion and not by pleading statutes.

¶ 17 The Oklahoma Supreme Court set forth the procedural requirements for the forum non conveniens motion requesting change of venue, noting that the procedural requirements and timing were not controlled by statute. We did not view this motion as one raising "improper venue" within the scope of the venue statutes. Just as 12 O.S. § 2012(B)(3) does not apply to a motion raising the judicial doctrine of forum non conveniens, neither does § 2012(B)(3) apply to a motion alleging a contractual agreement for a different venue.16

¶ 18 In Atlantic Marine Construction Co., supra, the U.S. Supreme Court noted that it need not consider application of Fed.R.Civ.P. 12(b)(6), and stated that "[e]ven if a defendant could use Rule 12(b)(6) to enforce a forum-selection clause, that would not change our conclusions that § 1406(a) and Rule 12(b)(3) are not proper mechanisms to enforce a forum-selection clause."17 The United States Court of Appeals for the Second Circuit has appeared to have construed this language to mean that a Federal Rule 12(b) motion is not a proper mechanism for enforcement of a valid forum-selection clause.18 Prior to Atlantic Marine Construction Co., supra, authors noted that the First, Second, Third, and Sixth Circuit Courts allowed forum-selection clauses to be enforced by Rule 12(b)(6) motion alleging "failure to state a claim," while the Fourth, Seventh, Ninth, Eleventh, and D.C. Circuit Courts allowed enforcement by a Rule 12(b)(3) motion alleging "improper venue."19 One author has noted: "But the [Supreme] Court has explicitly left open the possibility that using Rule 12(b)(6), and other means of raising forum clauses as an affirmative defense, may be `ultimately correct.'"20

¶ 19 Oklahoma currently has a statute addressing forum non conveniens. 12 O.S. § 140.3.21 However, no party to the present controversy argues that any language in § 140.3 requires its application to a forum-selection clause in a contract. We decline to make any holding on the application of the statute.22

¶ 20 The forum-selection clause in the case before us was not created by a statute, but by a contract made by these parties. Obligations created by parties in a contract are enforced as contractual rights in a legal proceeding that adjudicates a contract cause of action (and defenses thereto).23 Contractual obligations may be used by a defendant to avoid liability in a legal action on the contract, and they are usually presented in the legal contest in forms such as contesting plaintiff's alleged meaning of the language of the contract, disputes over contract formation, performance, or execution, as well as affirmative defenses and compulsory counterclaims. The dispute before us concerns the language in the contract and its judicial enforcement. We have indicated that judicial enforcement of the contract-based claims in a retainer agreement include enforcing contractually specified arbitration and venue selection.24 What we have before us is a dispute concerning the judicial enforcement of a contract-based obligation specifying venue selection, a merits-based issue on the meaning of a specific provision of a contract.

¶ 21 The Cochran Firm sought dismissal in the trial court. Because this is a dispute on the merits of the cause of action, it may be procedurally presented by either an appropriate § 2012(B)(6) motion challenging the sufficiency of the face of the petition,25 or by a motion for summary judgment seeking a judgment on the merits of a contract-based claim.26 The party that sought to invoke judicial relief based upon an alleged contractual agreement for venue selection is the defendant, the Cochran Firm, when it sought dismissal in the trial court. A burden to present facts, claims and legal arguments falls on the party who asserts an entitlement to the judicial relief sought.27 The Cochran Firm has the burden to file the appropriate § 2012(B)(6) motion to dismiss attacking facial sufficiency of the petition or a motion for summary judgment. Once Cochran's initial burden is satisfied, a burden is placed on Tucker to make the appropriate procedural and substantive response, as we now explain.

III.

¶ 22 A typical dispute involving the judicial doctrine of interstate forum non conveniens is not based upon the parties' agreement or the merits of a contract and does not involve a 12 O.S. § 2012(B)(6) procedure. Rather, the doctrine involves specific private and public interests. The U.S. Supreme Court stated that when a federal district court adjudicates a typical forum non conveniens motion the trial court must evaluate both the convenience of the parties and various public-interest considerations; and upon weighing the relevant factors the court should decide whether, on balance, a transfer would serve the convenience of parties and witnesses and otherwise promote the interest of justice.28

¶ 23 The High Court identified the parties' private interests as those including "relative ease of access to sources of proof; availability of compulsory process for attendance of unwilling, and the cost of obtaining attendance of willing, witnesses; possibility of view of premises, if view would be appropriate to the action; and all other practical problems that make trial of a case easy, expeditious and inexpensive."29 The Court identified the public-interest factors as including "the administrative difficulties flowing from court congestion; the local interest in having localized controversies decided at home; [and] the interest in having the trial of a diversity case in a forum that is at home with the law."30

¶ 24 In Conoco, Inc. v. Agrico Chemical Co., we cited a 1947 U.S. Supreme Court opinion and a 1954 opinion from this Court, and we explained that we also examine the public and private interests involved in a forum non conveniens dispute.31

Conoco, Inc. v. Agrico Chemical Co., 2004 OK 83, at ¶ 11, 115 P.3d at 833.32

¶ 25 In Atlantic Marine Construction Co., supra, the Court stated that a plaintiff's choice of venue should be considered when a court adjudicates a forum non conveniens motion.33 The doctrine of forum non conveniens recognizes the convenience of the parties and their interests in selecting and litigating in a particular judicial forum.34 However, in a circumstance of contract-based venue this interest has been expressed by them when they created an agreement stating their preference for a forum. As noted in Atlantic Marine, "The enforcement of valid forum-selection clauses, bargained for by the parties, protects their legitimate expectations and furthers vital interests of the justice system."35

¶ 26 In Conoco, Inc. v. Agrico Chemical Co., supra, this Court relied upon the U.S. Supreme Court's opinion in Gulf Oil Corporation v. Gilbert, supra, and stated that "Except where the balance of these [public and private] interests tilts strongly in favor of the defendant, the plaintiff's choice of forum should rarely be disturbed."36 A valid forum-selection clause is one of those instances where a plaintiff's choice of a forum at the time of litigation may be disturbed by plaintiff's previous contractual choice of a different forum for litigation. In Atlantic Marine Construction Co., supra, the Court stated that when a valid forum-selection clause is present, "... the plaintiff's choice of forum merits no weight. Rather, as the party defying the forum-selection clause, the plaintiff bears the burden of establishing that transfer to the forum for which the parties bargained is unwarranted."37 One reason for this is "the plaintiff has effectively exercised its `venue privilege' before a dispute arises" when the plaintiff and defendant made a valid agreement on the judicial venue of their dispute.38 Because the private interests in selecting a forum for disputes have been determined contractually between the parties, a party challenging the selection is usually left only two choices, challenging the validity of the forum-selection clause or showing that public interest or public policy requires non-enforcement of the clause.

¶ 27 Some courts have treated the validity of a forum-selection clause as an issue separable from the validity of the rest of the contract in which the clause appears; i.e., similar to the issue presented by the validity of an arbitration clause,39 a forum-selection clause's validity is considered separately from the validity of the rest of the contract in which it appears.40 Historically, this Court has recognized that a contract may possess severable parts and severability is determined by the particular circumstances in each case, "each case must depend very large on the terms and circumstances of the contract involved."41

¶ 28 Generally, a severable contract is susceptible of division and apportionment in its nature and purpose, and having two or more parts, not necessarily dependent on each other, nor so intended by the parties, in respect to matters and things contemplated and embraced in the contract; and whether a contract is entire or severable is primarily a question of intention be determined from language used by the parties and the subject matter of agreement.42 A contract with a forum-selection clause is separable in that the clause involves judicial enforcement of the contract instead of the usual contractual provisions concerning performance and the parties' obligations.

¶ 29 One example of separable clauses in a contract has occurred where courts examine arbitration clauses in a contract to determine if the clause itself is valid. In this sense and paraphrasing from the U.S. Supreme Court, when parties contractually commit to a particular venue to hear disputes arising from a contract, attacks on the validity of the contract, as distinct from attacks on the validity of the venue-selection clause itself, are to be resolved in the venue contractually agreed upon by the parties unless the venue-selection clause is invalid.43

¶ 30 We decline to decide whether the amended motion to dismiss filed by the Cochran Firm properly raised the issue of forum-clause validity, or was a request for summary judgment or a § 2012(B)(6) motion. Because of apparent confusion on the issue of § 2012(B)(6) conversion to a motion to summary judgment as such relates to the standard of review raised by the parties on certiorari, we note the following. This Court "has consistently stated that a motion to dismiss for failure to state a claim upon which relief may be granted, as provided by 12 O.S.2001 § 2012(B)(6), is to be treated as a motion for summary judgment when matters outside of the pleadings are presented in support of the motion and those extra-pled matters are not excluded by the trial court when the motion is considered."44 Further, a copy of any written instrument which is an exhibit to a pleading is a part thereof for all purposes.45 When a defendant files a § 2012(B)(6) motion with an incorporated exhibit which is relied on by plaintiff in the petition, or is integral to plaintiff's petition, the motion is not converted into one for summary judgment.46 The Cochran Firm filed an amended motion to dismiss with six attached exhibits, Tucker's Petition, an affidavit of a person employed by the Cochran Firm, the written contract, and three opinions from the U.S. District Court for the Northern District of Oklahoma. Whether the incorporated written contract is integral to Tucker's petition and therefore not used as a basis for conversion to summary judgment was not briefed by the parties. Additionally, a valid contract requires that there should be (1) parties capable of contracting, (2) their consent, (3) a lawful object, and (4) sufficient cause or consideration.47 When the Cochran Firm attached an affidavit of one of its employees to the motion to dismiss, the issue arises whether the language used by the defendant in its motion/affidavit was for the purpose of showing Tucker's contractual intent, knowledge, and consent and whether a prima facie valid forum-selection clause existed. In other words, was the Cochran Firm making an effort to show that (1) a written agreement on forum-selection satisfied these four necessary elements to a contract, (2) a prima facie forum-selection clause existed, and (3) the Cochran Firm was entitled to a dismissal on the issue of forum-selection because of this affidavit? Was the quest for dismissal converted to summary judgment by the Cochran Firm's use of the employee's affidavit?48 Tucker filed a response with an affidavit attached which included statements that he was not informed by the Defendant of the forum-selection clause in the Agreement, and that he did not negotiate or discuss the clause. Plaintiff attached a copy of the written agreement to his response for the purpose of showing that he did not place his initials next to the forum-selection clause. Was this filing sufficient to raise a factual issue in the context of summary judgment relating to the four elements to a contract as a necessary predicate for a valid forum-selection clause and thus making the issue one for a jury?49 Plaintiff's response, like Defendant's motion, did not provide the trial court with any discussion, guidance, or request that the issues framed by the parties be reviewed by the trial court using procedure for a § 2012(B) motion, motion for summary judgment, or some other standard. The motion and response do not comply with the requirements of Rule 13 of the Uniform Rules for District Courts. Summary judgment proceedings are governed by Rule 13.50 The trial court granted the motion to dismiss, apparently convinced by Defendant's brief that Tucker was required to show that enforcement was mandatory unless Tucker showed that enforcement of the forum-selection clause was "unfair and unreasonable under the circumstances."51 The judgment of the District Court appears to show that its decision was not based upon either § 2012(B)(6) or a summary judgment request. We decline to decide these issues raised by the parties in advance of them litigating their claims in the District Court utilizing a procedure that is proper for the nature of the claims they desire to litigate.52 We recognize that this Court has not previously given express guidance for the procedure counsel should use for litigating a forum-selection clause, but litigation of a contract-based claim of forum selection should be litigated as all legal claims, in the context of procedural rules guaranteeing that a legal claim may be "carried to an adjudication on the merits."53

¶ 31 No one may contract requiring conduct that is against public policy. 15 O.S. 2011 § 211.54 In Groendyke Transport, Inc. v. Cook, we explained that the judicial doctrine of forum non conveniens springs from the court's equitable powers and exercised when the interests of justice, including public policy, require.55 In the matter before us, Tucker's necessarily implied argument is that public policy requires negation of the forum-selection clause in this case and the substance of that public policy is found in (1) the "public interests" recognized by the doctrine of forum non conveniens, (2) the duties and responsibilities of a lawyer licensed to practice law in this state that were allegedly breached by the Cochran Firm, (3) general principles of contract law that were allegedly violated by the defendant, and (4) other allegations of wrongful conduct by the defendant.

¶ 32 As we previously noted, in Atlantic Marine Construction Co., supra, the Court stated that when a valid forum-selection clause is present, "as the party defying the forum-selection clause, the plaintiff bears the burden of establishing that transfer to the forum for which the parties bargained is unwarranted." The Court further explained that since the private interests were expressed by the forum-selection clause, a court should not consider arguments about the parties' private interests, but consider only the public interests: "As a consequence, a district court may consider arguments about public-interest factors only."56

¶ 33 We agree with placing this burden on the party challenging a forum-selection clause after a prima facie validity of the clause is shown by a party relying upon such a clause, if a party challenging this validity is unsuccessful on that challenge. This burden is consistent with our opinions explaining that only those contracts that are invalid on their faces or clearly tend against public policy are void, that a contract should receive such an interpretation as will make it lawful if such result is not clearly violative of the intent of the parties, and that one who asserts the invalidity of a contract has the burden of proof.57 The Cochran Firm argued in its reply to Tucker's response that his "burden of proof" required him to show that litigating in California was "unfair or unreasonable." While Tucker's public policy claim may include the traditional "unfair and unreasonable" claim as such relates to a public-interest recognized in traditional forum non conveniens doctrine; because the Cochran Firm is asserting a contractual right, Tucker may raise any cognizable contract-based claim, including a claim based on public policy, when that claim relates to the forum-selection clause itself as opposed to the contract as a whole.

¶ 34 In response to the Cochran Firm's motion, Tucker argued that the forum-selection clause was never negotiated, bargained for, or discussed by the parties, and that while several of the contractual provisions required a showing of Tucker's agreement by the placement of his initials in various places in the contract, there was no place for his initials to show agreement with the forum-selection clause. He also argued "Defendant has made no allegation that the Agreement was a negotiated contract." Tucker challenged whether his consent had been given to the forum-selection clause.58 Tucker also alleged fraud in his petition, and if fraud was present then a forum-selection clause should not be enforced since it would violate public policy. Of course, a forum-selection clause obtained by fraud is voidable.59 Tucker also alleged public policy was violated by a lack of professional ethics by the Cochran Firm. We decline to decide these issues prior to their litigation in the trial court using a proper procedure.

¶ 35 We need not address Tucker's and the Cochran Firm's additional arguments because we must remand this proceeding to the District Court to provide an opportunity for the parties to present their claims within the proper procedural framework. In Rogers v. Dell Computer Corp., we remanded the matter to the District Court for additional proceedings "[b]ecause we have not before addressed the procedure to be employed on applications to compel arbitration."60 We have not before addressed the procedure to be employed on a motion to enforce a venue-selection clause.

¶ 36 The procedure when a contract-specified venue is the subject of litigation is not the same as when a motion is filed seeking the application of the judicial doctrine of forum non conveniens. For example, in the usual dispute involving the judicial doctrine of forum non conveniens, if a trial court grants a motion to dismiss then the order is appealed as a final order as defined by 12 O.S. § 953.61 In the present appeal, the Court directed the parties to comply with the procedure provided by Okla. Sup.Ct. R. 1.36. This Rule provides a procedure for summary judgments and dismissals for failure to state a claim or lack of jurisdiction of a person or subject matter.62 While the substance of this appeal should be one from a § 2012(B)(6) motion/summary judgment, the parties had no notice that their trial court briefs would serve as briefs on appeal or that a forum-selection litigation contest was one subject to 12 O.S. § 2012(B)(6) and the requirements for a Rule 13 summary judgment. While the lack of notice concerning the function of Rule 1.36 and certain trial briefs serving as appellate briefs may be corrected by an appellate court within an appeal, the parties must be afforded notice with an opportunity to be heard on their litigable interests when an appellate court requires a judicial procedure in the trial court and that procedure allocates burdens of persuasion and proof.63 If the Cochran Firm's exhibits to its motion served to show prima facie validity of the forum-selection clause in support of the motion for § 2012(B)(6) relief or summary judgment, then Tucker had a burden to respond to the motion and argue the proper response to a § 2012(B)(6) motion or respond to a motion for summary judgment and present any material facts that were disputed, and argue that Cochran Firm's claim concerning the venue selection should not be granted as a matter of law.64 Remand will provide the parties the opportunity to litigate the issues within a proper procedure and with notice of that procedure.

IV.

¶ 37 We hold: (1) When a parties' agreement has an interstate forum-selection clause and a party seeks its judicial enforcement in an Oklahoma District Court by seeking dismissal of the Oklahoma proceeding, then the procedure for its enforcement is by a motion pursuant to 12 O.S. § 2012(B)(6), or Rule 13 motion for summary judgment; and (2) An interstate forum-selection clause is separable from the contract in which it appears, and its validity like any other provision in a contract is subject to the requirements of a valid contract.

¶ 38 The opinion by the Court of Civil Appeals is vacated. The judgment of the District Court is reversed, and the matter is remanded to that court for further proceedings consistent with this opinion.

¶ 39 CONCUR: REIF, V.C.J., WATT, WINCHESTER, EDMONDSON, TAYLOR, COMBS, GURICH, JJ.

¶ 40 CONCUR IN RESULT: KAUGER, J.

¶ 41 NOT PARTICIPATING: COLBERT, C.J.