WOMACK, J., delivered the opinion of the unanimous Court.

This is an appeal from a sentence that was enhanced under Penal Code Section 12.42(c)(2), which mandates a life sentence for a defendant convicted of a sex-related offense listed in Subsection (A) if the defendant has been previously convicted of a Texas offense listed in Subsection (B), or an offense "under the laws of another state containing elements that are substantially similar to the elements" of a Texas offense listed in Subsection (B).1 This case requires us to decide whether the California offense of sexual battery contains elements that are substantially similar to the elements of the Texas offenses of sexual assault or aggravated kidnapping. We hold that it does not.

I. Background

A Harris County jury found the appellant guilty of compelling prostitution2 and sexual assault of a child.3 The indictments for both offenses alleged that the appellant had been previously convicted in California of the felony offense of sexual battery.4 The jury found these allegations to be true. For compelling prostitution, the jury assessed punishment of 99 years in prison. For sexual assault of a child, the jury assessed punishment of life in prison pursuant to Section 12.42(c)(2).

This appeal is from only the sexual assault of a child case.

The appellant argued that the trial court erred in finding that California sexual battery was substantially similar to any of the enumerated offenses in Section 12.42(c)(2)(B), and therefore the trial court also erred in instructing the jury that a life sentence was mandatory for the sexual-assault-of-a-child conviction if the jury found the enhancement allegation to be true. In reply, the State argued that the elements of sexual battery were substantially similar to the elements of the enumerated offenses of sexual assault5 and aggravated kidnapping.6 The Court of Appeals held for the appellant.7 We granted the State's petition for discretionary review to determine whether the Court of Appeals erred in finding that sexual battery does not contain elements that are substantially similar to the elements of any of the enumerated offenses in Section 12.42(c)(2)(B), and whether the Court of Appeals consequently erred in finding that the trial court erred in submitting the enhancement instruction to the jury.

II. Interpreting "Substantially Similar"

Penal Code Section 12.42 provides enhanced penalties for repeat felony offenders. As we said in Griffith v. State, Section 12.42(c)(2) effectively creates a "two-strikes policy" for repeat sex offenders in Texas, embodying the legislature's intent to treat repeat sex offenders more harshly than other repeat offenders.8 Section 12.42(c)(2) mandates a life sentence for a defendant convicted of a sexual offense listed in Section 12.42(c)(2)(A) that he committed after having been previously convicted of any of the enumerated sexual offenses in Section 12.42(c)(2)(B), or "under the laws of another state containing elements that are substantially similar to the elements of an [enumerated] offense."9

While the phrase "substantially similar" has not been defined by statute, our precedent and established canons of statutory construction provide insight into its meaning. Our only case to apply the phrase to the laws of another state is Ex parte White.10 In White, the defendant had been previously convicted in Delaware of unlawful sexual contact in the second degree, which was committed "when [a person] intentionally has sexual contact with another person who is less than 16 years of age or causes the victim to have sexual contact with him or a third person."11 We found that the Delaware offense contained elements that were substantially similar to the elements of the Texas offense of indecency with a child, which is committed when, "with a child younger than 17 years and not the person's spouse, whether the child is of the same or opposite sex, the person: ... engages in sexual contact with the child or causes the child to engage in sexual contact ...."12

Our finding in White warranted no discussion, but it is helpful to compare the statutes that were involved. We held that the statutes were substantially similar despite three differences in the elements of the offenses: (i) the circumstance of the victim's age was different by one year; (ii) the Delaware offense did not contain an element that the victim was "not the person's spouse"; and (iii) the Delaware offense defined "sexual contact" as a touching which, "under the circumstances as viewed by a reasonable person, is intended to be sexual in nature,"13 whereas the Texas offense defined "sexual contact" as a touching, if committed "with the intent to arouse or gratify the sexual desire of any person."14 The one-year age difference provides a good example of elements that are substantially similar, but not identical. The absence of the spouse element in the Delaware offense shows that one offense need not have every element of the other. Finally, the difference in the specific intent shows that, while an element of the foreign offense can be proved by a fact that would be insufficient to prove the respective Texas element,15 the elements may still be substantially similar.

White thus provided helpful examples of how the phrase is applied, but did not attempt to provide a general interpretation of "substantially similar."

We may derive such a general interpretation by applying established canons of statutory construction relating to the text.16 Pursuant to such established canons of construction, we may presume that each word in the statute has a purpose, and that words not defined in the statute are used in their ordinary and common sense.17 In common usage, "substantial" means "to a large extent" while "similar" means "having a likeness or resemblance."18 Together with comparative words like "similar," "majority," or "probability," the combination with "substantial" or "substantially" means something significantly greater than the modified word, whereas with absolute words like "complete," "certain," or "all," the combination with "substantially" means something only slightly less than the modified word ("similar"). Based on this common usage, we hold that the elements being compared pursuant to Penal Code Section 12.42(c)(2)(B)(v) must display a high degree of likeness, but may be less than identical.

We are still left, however, with the critical question of the respect in which the elements must display a high degree of likeness. For example, elements could be substantially similar with respect to general characteristics such as terminology, function, and type19 of element, or with respect to specific characteristics such as the seriousness of violent or sexual aspects. The provisions guiding statutory construction in Penal Code Section 1.02, entitled Objectives of Code, suggest the answer to this question:

Therefore, based on the objectives in Penal Code Section 1.02, we further hold that the elements must be substantially similar with respect to the individual or public interests protected and the impact of the elements on the seriousness of the offenses.21

While we ultimately affirm the judgment of the Court of Appeals, we must clarify its interpretation of "substantially similar." First, "that a person guilty of the [foreign] law would also be guilty under the Texas law"22 is not a dispositive consideration. On the contrary, in White we found elements to be substantially similar despite the possibility that a person could be found guilty in Delaware on proof of facts insufficient to prove guilt in Texas.23 Also, this Court has not "held the elements of another state's law to be substantially similar to the elements of an [enumerated offense] when the elements of the other State's law parallel the elements of a single Texas offense."24 We have found no legal authority for this "parallel" test, and it seems of little assistance in applying the statute.

III. Application

We must first determine to which offense the appellant's prior conviction should be compared. Before trial, the State argued that the elements of sexual battery were substantially similar to the elements of aggravated kidnapping. In its reply on direct appeal, however, the State also compared sexual battery to sexual assault. The Court of Appeals discussed sexual assault, but it did not discuss aggravated kidnapping.25

In its petition for discretionary review, the State again argues sexual assault and aggravated kidnapping as alternative possibilities, and the appellant has responded to both possibilities. We shall therefore analyze whether the elements of sexual battery are substantially similar to the elements of either sexual assault under Section 22.011(a)(1) or aggravated kidnapping under Section 20.04(a)(4). We shall set out the full text of each offense and its defined terms, break the offenses into elements conducive to comparison, and then look for substantial similarity between elements.

A. California Sexual Battery

The appellant was previously convicted of a 1996 sexual battery under California Penal Code Section 243.4(a). Below are portions of the statute as it appeared at the time the appellant committed the offense in 1996:26

Subdivision (d) contained the root of the offense, which was a misdemeanor punishable by up to six months imprisonment.28 Subdivisions (a) through (c) included aggravating conduct or circumstances, which we have italicized in subdivision (a), and were felonies punishable by up to four years imprisonment.29 While the phrase "unlawfully restrained" was not defined by statute, California courts interpreted the phrase such that a person is unlawfully restrained "when his or her liberty is being controlled by words, acts or authority of the perpetrator aimed at depriving the person's liberty, and such restriction is against the person's will."30

For purposes of comparison, we will align and number the elements of the offense, together with statutory and judicial definitions, as follows:

B. Texas Sexual Assault

The offense of sexual assault is defined in Penal Code Section 22.011(a)(1) as follows:

Sexual assault is a second degree felony and as such is punishable by up to 20 years imprisonment.32

For purposes of comparison to sexual battery, the elements of sexual assault may be aligned and numbered according to the following two alternatives:

The offense of aggravated kidnapping under Penal Code Section 20.04(a) may be used as a previous conviction under Section 12.42(c)(2)(B) "if the defendant committed the offense with the intent to violate or abuse the victim sexually."33 Aggravated kidnapping is defined as follows:

Aggravated kidnapping is a first degree felony and as such is punishable by up to life or 99 years imprisonment.35 The Penal Code defines "abduct" to mean "to restrain a person with intent to prevent his liberation by: (A) secreting or holding him in a place where he is not likely to be found; or (B) using or threatening to use deadly force."36 "Restrain" means "to restrict a person's movements without consent, so as to interfere substantially with the person's liberty, by moving the person from one place to another or by confining the person."37 This Court has recognized that the intent to "violate or abuse [the victim] sexually" is not further defined within the Penal Code, but we have interpreted the element as an intent to commit a "non-consensual sex act" upon the victim.38

For purposes of comparison to sexual battery, the elements of aggravated kidnapping, together with statutory and judicial definitions, may be aligned and numbered as follows:

D. Analysis

Sexual battery does not contain elements that are substantially similar to the elements of sexual assault. The "touching" of an "intimate part" involved in elements II and III of the California offense encompasses a markedly different range of conduct than the "penetration or contact" of a person's "anus" or "sexual organ" involved in elements II and III of the Texas offense. Indeed, Section 243.4(f)(2) of the California Penal Code specifically excludes the California crimes of rape and sexual penetration from the scope of sexual battery. While the elements of the California and Texas offenses may be similar in a general sense, they do not display the high degree of likeness required to be substantially similar.

In addition, the individual interests protected by the sexual elements of the California offense are more like those interests protected by the Texas offense of assault under Section 22.01(a)(3)—protection from the offensiveness of the contact—rather than those of the Texas sexual assault statute and the California rape and sexual penetration statutes—protection from the severe physical and psychological trauma of rape. Furthermore, the difference in the sexual elements results in a much less serious California offense. Without the restraint involved in element IV, which is absent in sexual assault, sexual battery is a misdemeanor punishable by only six months imprisonment, while sexual assault is a second degree felony punishable by 20 years imprisonment.

Aggravated kidnapping presents a closer question. The difference between the sexual elements of the offenses is worth noting, in that sexual battery contains a conduct element requiring the touching of an intimate part, whereas aggravated kidnapping contains a specific intent element requiring the intent to commit a non-consensual sex act. More importantly, sexual battery requires only an "unlawful restraint," which is interpreted as the control of a person's liberty, against his will, by words, acts or authority of the perpetrator aimed at depriving the person's liberty.39 On the other hand, aggravated kidnapping requires an "abduction," which is an "unlawful restraint"—a substantial interference with the person's liberty, by moving the person from one place to another or by confining the person—committed with the specific intent to prevent the victim's liberation by secreting or holding him in a place where he is not likely to be found or using or threatening to use deadly force.40 The additional, substantive specific—intent component of "abduction" suggests that the restraint elements do not display a high degree of likeness.

The distinct individual interests protected by the restraint elements support this conclusion. The California "unlawful restraint" element protects individuals' liberty interests, while the Texas "abduction" element goes beyond protecting liberty interests to protect against the considerable risk of death or serious bodily injury involved in an abduction.41 Moreover, the difference between the restraint elements causes a great difference in the seriousness of the offenses, as demonstrated by the punishments available. Even with arguably more serious sexual elements, sexual battery exposes a defendant to a maximum sentence of four years, whereas aggravated kidnapping exposes a defendant to a maximum sentence of life or 99 years.42

We conclude that sexual battery does not contain elements that are substantially similar to the elements of aggravated kidnapping or sexual assault. We therefore affirm the judgment of the Court of Appeals and remand the case to the trial court for further punishment proceedings.