This is a declaratory judgment action in which the plaintiff seeks a determination that a patent held by the defendant is invalid, unenforceable, and not infringed. The plaintiff, Nova Biomedical Corporation, is a Massachusetts corporation located in Newton and engaged in the manufacture and sale of medical instruments. The defendant, Willi Moller, is a citizen and resident of Switzerland and owner of a sole proprietorship in Zurich, formerly known as Gebruder Moller Glasblaserei. On November 28, 1979, the district court dismissed the complaint, ruling that Nova had failed to establish personal jurisdiction over Moller pursuant to Mass. Gen. Laws Ann. ch. 223A, § 3, the Massachusetts long arm statute. We reverse.

The facts are undisputed. The patent in suit, which Moller acquired in 1970 from the Swiss inventor, covers an electrode capable, inter alia, of measuring potassium levels in fluids such as blood. Nova manufactures and sells a device which employs a similar electrode to perform the same function. On May 31, 1978, and again on March 16, 1979, Moller's attorneys wrote to Nova charging it with patent infringement; the first letter demanded that Nova "cease and desist" from such infringement, while the second suggested that a "prompt response" would avoid the "need for instituting litigation." Rather than following up on this threat, however, Moller filed a patent infringement suit on June 14, 1979, in the District of Columbia against two hospitals who had purchased the disputed electrode system from Nova. Five weeks later, Nova filed the present action for declaratory relief and for an injunction against the customer suit.

Moller's principal contact with Massachusetts consists of a cross-licensing agreement with a Massachusetts corporation called Orion Research Incorporated, covering the patent in suit, another patent owned by Moller, and a patent owned by Orion. Although this agreement was formally consummated in March of 1979 at Orion's headquarters in Cambridge, Massachusetts, its basic terms had been settled upon by 1976, and Orion had commenced payment of royalties the following year. In addition to granting licensing rights and specifying the level of royalty payments for each of the three patents, the agreement, inter alia, requires an exchange of quarterly reports concerning worldwide sales of the covered electrodes, permits Moller to inspect Orion's books in Massachusetts, obligates each party to inform the other of any suspected infringement by third parties, and provides that the law of Switzerland will be controlling.

Through the first quarter of 1979, Orion had paid to Moller just under $50,000 in royalties under the second of the Moller patents covered by the agreement. By contrast, although Orion has manufactured "thousands" of the electrodes covered by the patent in suit, it has never paid any royalties to Moller therefor; the agreement provides that such electrodes are royalty-free to the extent they are sold by Orion to end users, as opposed to other manufacturers. Orion does, however, owe some royalties for its sale of these electrodes. It estimates that $10,000 is due, but the precise amount is disputed by the two parties. Orion's use of the patent in suit also confers upon Moller the secondary benefit of a substantially royalty-free use of Orion's patented device. The electrodes sold by Moller under the Orion cross-licensed patent although ordinarily subject to a royalty are royalty-free to the extent they do not exceed twenty percent of the number of electrodes sold by Orion under the patent in suit during the same accounting period. By means of this reciprocal arrangement, therefore, even those electrodes sold by Orion under the patent in suit that are nominally royalty-free provide a monetary benefit to Moller.

Of Moller's remaining contacts with Massachusetts, the most substantial has consisted of the sale to Orion of various products and chemicals. The largest of these transactions has been Orion's purchase in March of 1979 of over $110,000 worth of pH electrodes, approximately one-third of which had been shipped to Boston by the end of September. In addition, within the past two years, Moller has sold to Orion almost.$19,000 worth of calcium ion exchanger and over $5,000 worth of sodium electrodes, connectors, and a chemical called valinomycin. All of these materials are unrelated to the electrodes covered by the patent in suit except for the chemical valinomycin, which is a component thereof. Moller and Orion have engaged in an extensive course of correspondence, devoted primarily to negotiation of the license agreement. Moller also has visited Massachusetts twice to confer with Orion personnel and to talk with another Massachusetts company concerning unrelated business. Finally, the defendant has negotiated in Switzerland with a third Massachusetts company regarding a license under the patent in suit. Moller maintains no office, representative, sales force, telephone, or bank account in Massachusetts and does not advertise in any publication distributed here.

A preliminary observation concerning the scope of the Massachusetts long arm statute is in order. In "Automatic" Sprinkler Corp. v. Seneca Foods Corp., 361 Mass. 441, 280 N.E.2d 423, 424 (1972), the Supreme Judicial Court described the function of this statute as "an assertion of jurisdiction over the person to the limits allowed by the Constitution of the United States." Yet even under this expansive view, all questions of long arm jurisdiction in Massachusetts do not collapse into a single constitutional inquiry. As the Court later explained:

G.L. c. 223A, § 3, asserts jurisdiction over the person to the constitutional limit only when some basis for jurisdiction enumerated in the statute has been established. Although presented with jurisdictional facts sufficient to survive due process scrutiny, a judge would be required to decline to exercise jurisdiction if the plaintiff was unable to satisfy at least one of the statutory prerequisites.

Good Hope Indus., Inc. v. Ryder Scott Co., 79 Mass.Adv.Sh. 1155, --- Mass. ---, 389 N.E.2d 76, 80 (1979); accord, Carlson Corp. v. University of Vermont, 80 Mass.Adv.Sh. 659, --- Mass. ---, 402 N.E.2d 483, 485 (1980). Thus, rather than giving way entirely to constitutional considerations, the statutory language imposes an additional set of constraints on a court's assertion of in personam jurisdiction. See, e. g., Singer v. Piaggio & C., 420 F.2d 679, 681 (1st Cir. 1970); North American Video Corp. v. Leon, 480 F. Supp. 213, 216-18 (D.Mass.1979).1

In each of the cases decided by the Supreme Judicial Court under Mass.Gen.Laws Ann. ch. 223A, § 3, the applicability of one of the statute's literal requirements was not seriously in question and the Court's attention was devoted to the constitutional inquiry. See Carlson Corp. v. University of Vermont, 402 N.E.2d at 485; Good Hope Indus., Inc. v. Ryder Scott Co., 389 N.E.2d at 80; Droukas v. Divers Training Academy, Inc., 375 Mass. 149, 376 N.E.2d 548, 551-53 (1978);2 "Automatic" Sprinkler Corp. v. Seneca Foods Corp., 280 N.E.2d at 425-26. The instant case presents the converse situation. There is little dispute that the assertion of jurisdiction would comport with due process, given Moller's extensive and ongoing contacts with the forum.3 See, e. g., Japan Gas Lighter Assoc. v. Ronson Corp., 257 F. Supp. 219, 233-36 (D.N.J.1966). At issue, instead, is whether the statutory prerequisite upon which Nova exclusively relies the "transacting business" provision has been satisfied. That section of the statute provides:

A court may exercise personal jurisdiction over a person, who acts directly or by an agent, as to a cause of action in law or equity arising from the person's

(a) transacting any business in this commonwealth . . . .

Mass.Gen.Laws Ann. ch. 223A, § 3(a). Two questions are presented: (1) whether the mailing of two letters charging patent infringement and threatening litigation constitutes the "transacti(on)" of "business"; and (2) whether Nova's cause of action can be viewed as "arising from" Moller's licensing arrangement with Orion. An affirmative answer to either will suffice to support jurisdiction.

Despite the paucity of pertinent Massachusetts case law, there are several indications that the "transacting any business" clause should be construed broadly. First, the Supreme Judicial Court has ruled that the provision is not limited to commercial activity by the defendant, but rather "is general and applies to any purposeful acts by an individual, whether personal, private, or commercial." Ross v. Ross, 371 Mass. 439, 358 N.E.2d 437, 439 (1976).4 Second, a liberal reading of section 3(a) is suggested by the Court's decision in Droukas, where the nonresident defendant's sale of two marine engines to the plaintiff, even though constituting "an isolated transaction" with "slight effect on the commerce of the Commonwealth,"5 376 N.E.2d at 551, apparently6 satisfied the "transacting business" requirement. Finally, as a general matter, the remedial nature of the long arm statute, see Kagan v. United Vacuum Appliance Corp., 357 Mass. 680, 260 N.E.2d 208, 210-11 (1970), argues for a liberal construction of its provisions. Zabin, The Long Arm Statute: International Shoe Comes to Massachusetts, 54 Mass.L.Q. 101, 117 (1969). Nevertheless, the "transacting business" requirement is not without some bite. In Nichols Assocs., Inc. v. Starr, 4 Mass.App. 93, 341 N.E.2d 909 (1976), the plaintiff attempted to sue a Connecticut resident to recover the value of services rendered under a surveying contract. Notwithstanding that (1) the plaintiff performed a portion of the surveying work at its Massachusetts office, and (2) the defendant occasionally dispatched an employee to the plaintiff's office to pick up plans, the Appeals Court concluded that the defendant was not "transacting any business" in Massachusetts within the meaning of section 3(a). Id. 341 N.E.2d at 912-13.

To support its contention that the mailing of two letters charging patent infringement and threatening litigation constituted the transaction of business, Nova relies principally on B & J Manuf. Co. v. Solar Indus., Inc., 483 F.2d 594 (8th Cir. 1973), cert. denied, 415 U.S. 918, 94 S. Ct. 1417, 39 L. Ed. 2d 473 (1974). The plaintiff there brought suit in its home forum of Minnesota against an Illinois corporation, seeking a declaratory judgment that a patent owned by the defendant was invalid and not infringed. The plaintiff attempted to assert personal jurisdiction under the "transacting business" provision of the Minnesota long arm statute, a provision which corresponds closely to its counterpart in the Massachusetts statute. The defendant's contacts with the forum consisted principally of (1) its advertisement in various publications distributed there, (2) the sale of various products, other than that covered by the patent in suit, to independent distributors located in Minnesota, and (3) its maintenance of "trouble shooters" in or near the state to assist users of the company's products. In addition, the defendant had written several letters to the plaintiff, charging it with infringement and threatening suit if the plaintiff refused to discontinue the manufacture and sale of its competing product. The court concluded that the statutory requirements had been met:

(T)here is no doubt but that the requests and threats were designed to reduce competition and thereby improve defendant's marketing and economic position. As such, we are convinced that the sending of these letters did, in a very real sense, constitute a transaction of business in Minnesota.

Id. at 598. After determining that the defendant's various contacts with the forum, when viewed together, were sufficient to satisfy due process, the court sustained jurisdiction.

The court below dismissed the B & J decision as "not persuasive," and the reaction of other courts has been decidedly mixed.7 Nonetheless, although its application to the facts of that case gives us slight pause,8 we think the Eighth Circuit's rule has substantial merit in appropriate circumstances. The mailing of a letter charging patent infringement and threatening litigation is clearly a "purposeful" act by the defendant. Ross v. Ross, 358 N.E.2d at 439. And although such an action, by itself, represents but an isolated and transitory contact with the forum, that is all the statute requires: in Carlson Corp. v. University of Vermont, 402 N.E.2d at 485, the Supreme Judicial Court found that the defendant had transacted business based solely on a single visit to Massachusetts to sign a construction contract. But we need not, and indeed should not, attempt to identify all the circumstances in which the sending of such a letter will constitute the transaction of business within the meaning of section 3(a); the scope of that term "must be decided on the particular facts involved." Droukas v. Divers Training Academy, Inc., 376 N.E.2d at 553. It is enough here to conclude that the statutory requirement is met (1) where the defendant already is conducting or planning some patent-related business activity in the forum, whether directly, by engaging in the manufacture or sale of products, or indirectly, by receiving royalties from a licensee who is so engaged, and (2) where the plaintiff is pursuing a competing line of work there. In these circumstances, the mailing of a letter that charges infringement and threatens suit can reasonably be considered an attempt "to reduce competition and thereby improve defendant's marketing and economic position." B & J Manuf. Co. v. Solar Indus., Inc., 483 F.2d at 598. In fact, given their common source and potential impact on one another, we think it justifiable in this context to view a charge of infringement as an extension or a component of the defendant's patent-related business activities in the forum9 particularly where, as here, the patentee and licensee have collaborated closely on the question of the plaintiff's alleged infringement.10 Under this approach, a mailed notice of infringement in the context described clearly would satisfy the statutory prerequisite.

It is argued that any rule which automatically subjects a patentee to foreign jurisdiction whenever he demands recourse from an infringer would be both undesirable and unfair. The argument runs as follows. First, such a rule would discourage the giving of written notice of patent infringement and lead to the filing of suit without warning "the blitzkreig nature of the attack being necessary to avoid vulnerability to foreign jurisdiction." Conwed Corp. v. Nortene, S. A., 404 F. Supp. 497, 506 n.8 (D.Minn.1975). Concomitantly, it would discourage the settlement of disputes. Alternatively, it is noted that a patentee is under some compulsion to provide written notice of infringement; not only do the patent laws anticipate that such notice "will be routinely sent prior to litigation," id., but a patentee's failure to do so may sharply limit his recoverable damages. See 35 U.S.C. § 287 (1970); Dunlap v. Schofield, 152 U.S. 244, 14 S. Ct. 576, 38 L. Ed. 426 (1894). See also Advanced Hydraulics, Inc. v. Otis Elevator Co., 525 F.2d 477, 480-82 (7th Cir.), cert. denied, 423 U.S. 869, 96 S. Ct. 132, 46 L. Ed. 2d 99 (1975) (laches and estoppel). Thus, to subject a patentee to foreign jurisdiction on this basis is said to be unfair.

We do not dispute the force of these legitimate, albeit contradictory, concerns. For two reasons, however, we do not consider them seriously threatened by the conclusion reached here. First, mailing a letter charging infringement and threatening suit is already a two-edged sword; it is well-established that such conduct creates an "actual controversy" and thus gives rise to a cause of action under the Declaratory Judgments Act, 28 U.S.C. § 2201 (1970). E. g., Brisk Waterproofing Co. v. A. Belanger & Sons, Inc., 209 F.2d 169, 170 (1st Cir. 1954). The question of where a patentee can be sued while admittedly important, see Codex Corp. v. Milgo Electronic Corp., 553 F.2d 735, 738 (1st Cir.), cert. denied, 434 U.S. 860, 98 S. Ct. 185, 54 L. Ed. 2d 133 (1977) would seem subordinate to that of whether it can be sued at all.11 Thus, our conclusion should affect only marginally a patentee's decision whether or not to send a notice of infringement.

More importantly, we do not hold here nor did the court in B & J Manufacturing that "sending threatening infringement letters into the forum district suffices to succumb to that district's jurisdiction." Cascade Corp. v. Hiab-Foco AB, 200 U.S.P.Q. 594, 595 (D.Or.1977), aff'd on other grounds, 619 F.2d 36 (9th Cir. 1980) (footnote omitted) (description of B & J holding). What we do hold is that such conduct can, in certain circumstances, constitute the transaction of business within the meaning of the Massachusetts long arm statute. Whether a patentee is thereafter subject to jurisdiction will depend on whether he possesses sufficient contacts with the forum to satisfy due process. While it is unnecessary for us to reach the question in light of Moller's extensive contacts with Massachusetts, see note 3 supra, we note that the mailing of an infringement notice standing alone has rarely been deemed sufficient to satisfy the constitutional standard. See note 7 supra.

In light of the facts described and with particular reference to Moller's receipt of royalties from Orion's use of the patent in suit and the competitive positions of Nova and Orion we conclude that Moller's threatening infringement notices to Nova constituted a transaction of business under section 3(a) giving rise to the present cause of action. With the requirements of both the long arm statute and due process satisfied, the district court can properly assert in personam jurisdiction over the defendant.

Nova has sought two additional forms of relief: an injunction against further proceedings in the District of Columbia action and a modification of a protective order issued by the district court. We prefer to let the lower court address these issues initially. Although, on the present record, this case would appear to invoke the "rebuttable presumption" recognized in Codex Corp. v. Milgo Electronic Corp., 553 F.2d at 738, we think any decision as to an injunction should be made after consideration of any recent developments. With respect to the scope of the protective order, the lower court expressly declined to reconsider this issue in the belief that it lacked jurisdiction. We think it should have a chance to do so, particularly because a question of mootness has subsequently emerged.

Reversed and remanded.