¶1 The State appeals, arguing that the trial court erred in dismissing, on mandatory joinder and *98double jeopardy grounds, James Green’s charge for failure to register as a sex offender. We affirm.
FACTS
¶2 Green, a convicted level II sex offender, is required to register every 90 days under RCW 9A.44.130. He registered as required with the Pacific County sheriff on April 9,2007, but he failed to report again until April 29, 2008.
¶3 The State charged Green with one count of failing to register as a sex offender, with the date of the alleged offense as “on or about July 9, 2007.” Clerk’s Papers (cause number 08-1-00054-9) (CP) at 7; RCW 9A.44.130(7). In September 2008, the trial court held a bench trial and found Green not guilty because the State failed to prove an “essential element” of the offense that Green had a “fixed residence” on or about July 9, 2007. CP at 28.
¶4 By amended information, the State again charged Green with one count of failing to register as a sex offender, with the date of the alleged offense listed as “on or about October 8, 2007.” CP at 12. He moved to dismiss, arguing that the State’s filing of another case against him for the same offense violated the mandatory joinder rule under CrR 4.3.1 and the constitutional prohibition against double jeopardy.
¶5 The trial court agreed with Green and dismissed the case. The State appeals.
ANALYSIS
¶6 The State contends that the trial court erred in holding that mandatory joinder and double jeopardy barred Green’s prosecution. The State further contends that under the separation of powers doctrine, a trial court may not prevent the prosecutor from exercising its discretion in *99making charging decisions. On the double jeopardy argument, we disagree.1
¶7 The double jeopardy clauses of the United States and Washington State Constitutions protect a defendant from multiple convictions for the same crime. U.S. Const, amend. V; Wash. Const, art. I, § 9; State v. Tvedt, 153 Wn.2d 705, 710, 107 P.3d 728 (2005). Double jeopardy protections are also implicated where the State seeks to subject the defendant to a second trial for the same offense. See United States v. Scott, 437 U.S. 82, 87-88, 98 S. Ct. 2187, 57 L. Ed. 2d 65 (1978). We review constitutional challenges de novo. State v. Jones, 159 Wn.2d 231, 237, 149 P.3d 636 (2006).
¶8 In order to determine whether a defendant’s rights against double jeopardy were violated, we must determine what “unit of prosecution” the legislature intended to be the punishable act. State v. Adel, 136 Wn.2d 629, 634, 965 P.2d 1072 (1998). The “unit of prosecution” refers to the scope of the criminal act. Adel, 136 Wn.2d at 634. Our analysis requires that we look first to the statute’s plain language and, if necessary, to the legislative history. State v. Durrett, 150 Wn. App. 402, 406, 208 P.3d 1174 (2009).2 But if the legislature’s intent is unclear, the rule of lenity requires us to construe any ambiguities in the defendant’s favor. State v. Bobic, 140 Wn.2d 250, 261-62, 996 P.2d 610 (2000).
¶9 RCW 9A.44.130 imposes a general duty on sex offenders to register. And RCW 9A.44.130(7), which relates specifically to Green’s duty, states in pertinent part:
All offenders who are required to register pursuant to this section who have a fixed residence and who are designated as *100a risk level II or III must report, in person, every ninety days to the sheriff of the county where he or she is registered.
The State charged Green under RCW 9A.44.130(ll)(a), which provides that “[a] person who knowingly fails to comply with any of the requirements of this section is guilty of a class B felony.”
¶10 It is unclear from the statute’s plain language whether the duty to register “in person, every ninety days” establishes the “unit of prosecution” as each 90-day period in which an offender with a fixed residence fails to register or treats the failure as an ongoing course of conduct. RCW 9A.44.130(7). Division One considered a similar question in Durrett and found the statute ambiguous, construing it in the defendant’s favor.3 150 Wn. App. at 410.
¶11 The State argues in part that one of the operative terms in RCW 9A.44.130(1l)(a) is the word “any” which establishes separate discrete violations for each 90-day period Green failed to register. But in Durrett, the court recognized that “any” is often construed to mean “every” and “all” rather than “one.” 150 Wn. App. at 408-09. The State also argues generally that the legislature’s intent in establishing the registration requirements was to assist law enforcement agencies in protecting the public and that construing the statute as creating discrete violations fulfills that intent. And the State noted that under Blockburger v. United States, 284 U.S. 299, 304, 52 S. Ct. 180, 76 L. Ed. 306 (1932), the 90-day difference between each charge is “more than sufficient to establish the second crime as separate and distinct.” Appellant’s Br. at 17-18. But Block-burger articulated that in the case of a single “ ‘impulse,’ ” only “ ‘one indictment lies.’ ” 284 U.S. at 302 (quoting I *101Francis Wharton, A Treatise on Criminal Law § 34 (11th ed. 1912)). The State’s arguments do not persuade us.
¶12 Green recites a few statutory provisions to support his argument that we should construe his failure to register as a continuing course of conduct. In order to ensure that a convicted sex offender avoiding detection by failing to register could not outrun the statute of limitations, the legislature established that “[u]nless relieved of the duty to register pursuant to this section, a violation of RCW 9A.44.130 is an ongoing offense for purposes of the statute of limitations under RCW 9A.04.080.” RCW 9A.44.140(6). And under RCW 9A.44.130(4)(c), the legislature explicitly established that “[a]n arrest on charges of failure to register, service of an information, or a complaint for a violation of this section, or arraignment on charges for a violation of this section, constitutes actual notice of the duty to register.”4
¶13 In light of these statutory provisions and Division One’s reasoning and holding in Durrett, we construe the duty to register every 90 days as creating an ongoing course of conduct that cannot support separate charges. Furthermore, the facts of this case support our “unit of prosecution” determination. In this instance, Green first violated RCW 9A.44.130(ll)(a) on or about July 9,2007. He committed an ongoing and continuing offense from that point until he registered again on April 29, 2008. It was not until after April 29 that the State charged him for the first time.
¶14 The State’s argument that the failure to register for each 90-day period after Green failed to register constitutes a separate charge is based on a flawed reading of RCW 9A.44.130. The State may file another charge for new failure to register conduct, so long as the continuing course of conduct of a prior failure to register has ended.
*102¶15 The trial court properly dismissed the charge for failure to register.5
¶16 Affirmed.
Quinn-Brintnall, J., concurs.Judge Elaine Houghton is serving as a judge pro tempore of the Court of Appeals pursuant to ROW 2.06.150.
Because we affirm the trial court’s dismissal based on double jeopardy grounds, we do not discuss the applicability of the mandatory joinder rule or the separation of powers doctrine.
Durrett is directly on point and leads us to resolve the double jeopardy issues here in Green’s favor. We also note that Division One issued its opinion in Durrett on June 1,2009, more than three months after the State submitted its brief in this case.
Durrett involved a defendant convicted of two counts of failure to register as a sex offender. 150 Wn. App. at 405. The State charged Durrett for failing to report weekly from December 6, 2006, through January 22, 2007, and also charged him for failing to report weekly from November 6 through November 17,2006. Durrett, 150 Wn. App. at 405. The jury found Durrett guilty on both charges. Division One held that Durrett’s two convictions violated double jeopardy and that the rule of lenity required the court to construe the punishable offense as the continuing course of conduct. Durrett, 150 Wn. App. at 404-05, 410.
We also note that federal courts have similarly held that the failure to register is a continuing offense under the Sex Offender Registration and Notification Act, 18 U.S.C. § 2250. See United States v. George, 579 F.3d 962, 964, 968 (9th Cir. 2009).
The dissent disagrees with our holding in line with Durrett, that Green’s failure to register constituted an ongoing and continuing offense until he registered again on April 29, 2008. Dissent at 101. But the dissent fails to sufficiently demonstrate that the legislature clearly intended to establish a discrete “unit of prosecution” every 90 days. Instead, the dissent’s disagreement proves our point that the statute is ambiguous. We, therefore, must construe the statute in Green’s favor.