Opinion for the court filed by Circuit Judge HENDERSON.
The Metropolitan Police Department (MPD) of the District of Columbia (District) arrested the appellants, John Doe and Jane Doe I, II, III and IV, for underage possession and/or consumption of alcoholic beverages. The Does appeal the district court’s dismissal of their consequent constitutional claims brought against the MPD and various D.C. officials. They argue that, because, their arrests and detentions were based on their violation of a civil statute, probable cause to believe a crime had been committed did not exist; accordingly, the MPD’s actions violated their Fourth Amendment rights. Because the version of the underage possession/consumption law in effect when John Doe was arrested was not unambiguously a civil offense, we affirm the district court’s dismissal albeit on a different ground. The version of the law under which the. four Jane Does were arrested, however, described an unambiguously civil offense and we therefore reverse the district court’s dismissal of their claims and remand those claims for further proceedings.
I.
A. Factual Background
Between September 2000 and October 2003, MPD officers arrested each of the five Does, all under 21 years of age at the time of arrest, for allegedly violating the District’s law prohibiting underage possession and/or consumption of alcoholic bever *462 ages. 1 In September 2000 John Doe was walking down H Street N.W. carrying a package of closed containers of beer. 2 He was approached by a uniformed MPD officer who placed him under arrest. The officer took him to the police station where he was held for seven hours. Before being released, he was issued a citation to appear in court to answer a single charge of violating the underage possession law, D.C.Code § 25-130. 3 The MPD arrested the four Jane Does between October 9 and October 11, 2003, pursuant to D.C.Code § 25-1002(a), the 2001 version of the underage possession and/or consumption law. 4 Jane Doe I was arrested at a pub after undercover MPD officers were told she was consuming an alcoholic beverage belonging to another pub patron. The officers removed her from the pub, arrested and handcuffed her, and transported her to the police station. She was held for more than three hours, issued a citation for underage consumption of alcohol and released. MPD officers arrested the other three Jane Does while they were walking together down Wisconsin Avenue N.W. carrying paper bags of closed containers of alcoholic beverages. The three were arrested, their belongings were searched and they were taken to the police station. Each was held for more than three hours and, before being released, each was issued a citation for underage possession of alcohol.
In November 2003, the five Does filed a six-count complaint, individually and on behalf of a class of similarly situated persons, 5 against the MPD, the D.C. Office of the Attorney General, Mayor Anthony Williams and D.C. Corporation Counsel Robert Spagnoletti in them official capacities only, Chief of Police Charles H. Ramsey and Lieutenant Patrick Burke in their individual and official capacities, and an unspecified number of unidentified arresting officers in their individual and official capacities (collectively the District). They alleged the District’s actions were unconstitutional under both the Fourth and Fifth Amendments to the United States Constitution and they sought equitable relief and money damages under 42 U.S.C. § 1983. The Does claimed that an arrest made under D.C.’s underage possession/consumption law was unlawful because the law set forth a civil, not criminal, offense; they were therefore arrested without probable cause in violation of the Fourth Amendment. 6 The Does asserted federal question jurisdiction under 28 U.S.C. §§ 1331 and 1343 and supplemental jurisdiction over various common law tort claims under 28 U.S.C. § 1367. 7 The Does also sought a temporary restraining order (TRO) and preliminary injunctive relief to prohibit the MPD from making any arrest *463 in the future under the underage possession/consumption law.
The District opposed the TRO petition, arguing that the district court lacked jurisdiction based on our decision in
Barwood, Inc. v. District of Columbia,
On January 28, 2004, the district court dismissed the complaint under Federal Rule of Civil Procedure 12(b)(1), concluding that “[f]or a Fourth Amendment violation to arise, the arrest must violate the Fourth Amendment of its own accord, for some reason other than the mere fact that the arrest was unauthorized under state law.” John Doe v. District of Columbia, No. 03-2379, at 6 (D.D.C. Jan. 28, 2004). Because Barwood held that an arrest unauthorized under state law does not constitute a Fourth Amendment violation, the Does’ “Fourth Amendment claims do not form a basis on which the Court can exercise jurisdiction over Plaintiffs’ suit.” Id. The Does timely appealed.
B. Statutory Background
In 1984, in response to federal legislation reducing transportation funding to any state that did not raise its legal drinking age to 21, see 23 U.S.C. § 158, the Council of the District of Columbia (D.C.Council) enacted a statute making it unlawful for any person under 21 to consume alcohol or for anyone to sell alcohol to any person under 21. Any underage person who misrepresented his age in order to purchase alcohol was guilty of a misdemeanor, subject to a $25 fíne or imprisonment for up to 10 days in the event of non-payment. D.C.Code § 25-130 (1991). In 1994 the Council amended section 25-130 to prohibit anyone under 21 years of age from possessing, purchasing or consuming alcoholic beverages. It also added a revocation of driving privileges penalty for violation of the law. D.C.Code § 25-130 (1995) (1994 law). The 1994 law deleted the misdemeanor offense of false representation of age; instead, it incorporated by cross-reference section 25-132, the catch-all provision of the District’s Alcohol Beverage Control Act (ABC Act), which provided for imprisonment of up to one year for any violation thereof. See D.C.Code § 25-831 (2005) (formerly D.C.Code § 25-132 (1981)).
The following year, in
District of Columbia v. Morrissey,
In 1997, the D.C. Council again amended section 25-130. See D.C.Code § 25-130(a) *464 (1997 law). 9 The 1997 law no longer cross-referenced section 25-132 and instead added specific penalties for statutory violations, including a “civil ” fine, “as an alternative sanction for any infraction.” D.C.Code § 25-130(b-2) (emphasis added). The Council included a criminal penalty for misrepresenting one’s age in order to purchase alcohol; anyone under 21 who did so was guilty of a misdemeanor and subject to a $300 fine or imprisonment not to exceed 30 days for non-payment. See D.C.Code § 25-130(b-l). Despite the deletion of the reference to section 25-132 and notwithstanding the alternative civil fine sanction, the District continued to follow Morrissey, prosecuting underage possession violators criminally as it had under the 1994 law. As noted, the 1997 law was in effect when John Doe was arrested in September 2000.
In October 2000, Brett Cass, who had been convicted of underage possession of alcohol under the 1997 law and sentenced to probation, challenged his conviction, claiming the statute prescribed only a
civil
penalty for underage possession. In a decision issued three years later, the D.C. Court of Appeals found the 1997 law’s criminal sanction inapplicable to underage possession and therefore concluded that a violation of subsection (a) of section 25-130 constituted a civil offense.
Cass v. District of Columbia,
Before the
Cass
decision, but after Cass brought his lawsuit, the District amended
*465
section 25-130 yet again.
See
D.C.Code § 25-1002 (2001) (2001 law).
10
The 2001 law had been enacted by the time the
Cass
opinion issued but the court in
Cass
made clear that its opinion did not decide any issue under the statute as amended, that is, under the 2001 law.
See Cass,
II.
A. Jurisdiction
We review de novo the dismissal of a complaint for lack of subject matter jurisdiction.
Empagran S.A. v. F. Hoffman-LaRoche, Ltd.,
The proper disposition of a complaint like the
Barwood
complaint — and the one we ultimately followed in that case, notwithstanding initially using 12(b)(1) language
13
— is not a dismissal based on lack of jurisdiction inasmuch as section 1983 itself provides the basis for federal question jurisdiction under 42 U.S.C. § 1331 and the court must assume jurisdiction before deciding whether a cause of action exists.
See Bell v. Hood,
In Barwood, whether or not a suburban taxicab driver could be arrested for violating the criminal reciprocity regulation depended on the regulation’s validity and its validity depended on whether or not the regulation had been properly adopted — an issue of state law that no law enforcement officer could be expected to resolve. Accordingly, the invalid enactment claim was insufficient to state a cause of action under the Constitution. By the same token, if an arrest under a federal criminal statute were similarly challenged on the ground that it had been invalidly enacted, a constitutional claim would not lie. If the underlying statute — federal or state — were plainly civil, however, Barwood would be inapplicable and a challenge to an arrest thereunder would state a Fourth Amendment cause of action.
Barwood’s relevance here, therefore, turns on whether the relevant underage possession and/or consumption law — both the 1997 and the 2001 versions — unambiguously made underage possession or consumption a civil offense. If it did, the Does are correct in maintaining that Bar-wood is inapplicable. If, however, the law’s civil nature was unclear, the District correctly asserts that Banvood would preclude the Does’ cause of action because it would hinge on a state law issue, that is, whether the law created a civil or criminal offense. With these principles in mind, we turn first to John Doe’s arrest which, as noted earlier, was based on the 1997 law.
B. John Doe
Given that John Doe’s arrest took place almost three years before the
Cass
decision, which interpreted the 1997 law to create a civil offense, the Does cannot argue that the 1997 law was “by definition” civil at the time of John Doe’s arrest.
15
As the court in
Cass
noted, the 1997 law’s cross-references to the punishments located in different sections and subsections “lead the reader in a circle,”
Cass,
Because the 1997 law was ambiguous as to whether underage possession constituted a crime, however, probable cause existed for the MPD officer to arrest John Doe. Whether probable cause exists is determined by looking at all of the facts and circumstances at the time of the arrest, including the knowledge and experience of the arresting officer.
See United States v. Kayode,
C. Jane Does (I, II, III and IV)
The arrest of the four Jane Does under the 2001 law is another matter. That law, unlike the one governing John Doe’s arrest in 2000, plainly establishes the underage possession and/or consumption of alcohol as a civil offense. In the 2001 version, the Council amended the civil fines provision to provide that any person who violates subsection (a) “shall ” be subject to “the following civil penalties” as an “alternative” to the misdemeanor penalty imposed for false representation of one’s age. § 25-1002(e)(l) (emphases added). The change removed any ambiguity regarding whether a violation of subsection (a) — the underage possession and/or consumption provision — constituted an offense to which the misdemeanor penalty included in subsection (c) for misrepresenting one’s age could apply. The plain language of the 2001 law manifested that it could not; application of the “alternative” misdemeanor sanction to a violation of subsection (a) was not permitted as it could have been under the 1997 law.
The four Jane Does, as alleged violators of subsection (a) — but not (c) — of the 2001 law, were subject to the civil penalties of subsection (e) and the additional revocation of driving privileges penalty of subsection (d). The newly-added subsection (e)(2) also supports the facially civil nature of the underage possession and consumption prohibition by providing that “officers of the Metropolitan Police Department may enforce the provisions of this subsection by issuing a notice of civil infraction for a violation of subsections (a) or (b) of this section.” § 25-1002(e)(2) (emphasis added). Subsequent interpretations by the D.C. Superior Court, while too late to give notice to the MPD of the civil nature of a violation of subsection (a) at the time the four Jane Does were arrested in 2003, also support our conclusion. See, e.g., District of Columbia v. Kaplan, Crim. No. D-1042-03, at 6-7 (D.C.Super.Ct. Dec. 24, 2003); District of Columbia v. Rothkoff, No. D-1896-01, at 5-7 (D.C.Super.Ct. Nov. 7, 2003).
Because the four Jane Does were arrested for a civil offense, their claims state a cause of action under the Fourth Amendment. The district court’s dismissal of their complaint is therefore reversed and their case is remanded for further proceedings. 19
*470 III.
For the foregoing reasons, we affirm the district court’s dismissal of John Doe’s claim pursuant to Federal Rule of Civil Procedure 12(b)(6) and with prejudice. We reverse the dismissal of the four Jane Does’ claims and remand for further proceedings consistent with this opinion.
So ordered.
Notes
. The statute changed from 2000 to 2003, as we discuss infra.
.
We base the background facts on the allegations of the complaint.
See Wagener et al. v. SBC Pension Benefit Plan,
. John Doe was arrested under the 1997 version of the law. See note 9 infra for text.
. See note 10 infra for text.
. The district court dismissed the action before the plaintiffs moved for class certification. See John Doe v. District of Columbia, No. 03-02379, at 2 (D.D.C. Jan. 28, 2004).
. The Does do not argue their Fifth Amendment claim before us.
. The tort claims included false imprisonment, false arrest, negligence, assault and battery, intentional infliction of emotional distress and malicious prosecution. See Compl. ¶¶ 152-82.
. The writing judge included the
dictum
in a separate section at the end of the opinion entitled "Judge Schwelb’s Views.”
Morrissey,
. The relevant text of the 1997 law is as follows:
§ 25-130. Purchase, possession, or consumption by persons under 21; misrepresentation of age; penalties.
(a) No person who is under 21 years of age shall purchase, attempt to purchase, possess, or drink any alcoholic beverage in the District ....
(b) No person shall falsely represent his or her age, or possess or present as proof of age an identification document which is any way fraudulent, for thq purpose of procuring an alcoholic beverage in the District, (b — 1) Any person under 21 years of age who falsely represents his or her age for the purpose of procuring any alcoholic beverage shall be deemed guilty of á misdemean- or and be fined for each offense not more than $300, and in default in the payment shall be imprisoned not exceeding 30 days. (b-2) A civil fine may be imposed as an alternative sanction for any infraction of this section ....
(c)In addition to the penalties provided in subsections (b-1) and (b-2) of this section, any person who violates any provision of this section shall be subject to the following additional penalties:
[ (l)-(3): setting out revocation of driving privilege penalties].
. The relevant text of the 2001 law is as follows:
§ 25-1002. Purchase, possession, or consumption by person under 21; misrepresentation of age; penalties.
(a) No person who is under 21 years of age shall purchase, attempt to purchase, possess, or drink an alcoholic beverage in the District ....
(b)(1) No person shall falsely represent his or her age, or possess or present as proof of age an identification document which is in any way fraudulent, for the purpose of purchasing, possessing, or drinking an alcoholic beverage in the District.
(2) No person shall falsely represent his or her age, or possess or present as proof of age an identification document which is in any way fraudulent, for the purpose of purchasing, possessing, or drinking an alcoholic beverage in the District.
(3) For the purpose of determining valid representation of age, each person shall be required to present to the establishment owner or representative at least one form of valid identification, which shall have been issued by an agency of government (local, state, federal, or foreign) and shall contain the name, date of birth, signature, and photograph of the individual.
(c) Any person under 21 years of age who falsely represents his or her age for the purpose of purchasing, possessing or drinking an alcoholic beverage shall be deemed guilty of a misdemeanor and, upon conviction, shall be fined for each offense not more than $300; provided, that in default of the payment of the fine, the person shall be imprisoned for a period not exceeding 30 days.
(d) In addition to the penalties provided in subsection (c) of this section, any person who violates any provision of this section shall be subject to the following penalties: [ (l)-(3): setting out revocation of driving privileges penalties],
(e)(1) As an alternative sanction to the misdemeanor penalties provided in subsection (c) of this section, a person who violates subsection (a) or (b) of this section shall be subject to the following civil penalties:
(A) upon the first violation, a penalty of $300;
(B) upon the second violation, a penalty of $600; and
(C) upon the third and subsequent violations, a penalty of $1,000 and the suspension of his or her driving privileges in the District for one year.
(e)(2) ABRA inspectors or officers of the Metropolitan Police Department may enforce the provisions of this subsection by issuing a notice of civil infraction for a violation of subsections (a) or (b) of this section in accordance with Chapter 18 of Title 2. A violation of this subsection shall be adjudicated under Chapter 18 of Title 2.
(Emphases added.)
. The statute was amended yet again in 2004. See D.C.Code § 25-1002 (2004).
. The District claimed that the authority to arrest a violator of the reciprocity regulation came from the District’s General License Law, providing that “any person violating ... any regulation made by the Council under the authority of this chapter shall upon conviction be fined not more than $300 or imprisoned for not more than 90 days.” D.C.Code. § 47-2846; Barwood, Inc. v. District of Columbia, No. 98-1901, at 6 (D.D.C. Feb. 16, 1999).
.
See Barwood,
. Although the court in Barwood assumed that it had jurisdiction to decide whether a constitutional claim had been alleged, its wording was less than clear. See supra note 13. Because of the ambiguity, the district court mistakenly assumed that the Barwood court had held that it lacked jurisdiction. See Doe v. District of Columbia, No. 03-2379, at 6 (D.D.C. Jan 28, 2004).
. They nevertheless state — without supporting argument — that the 1997 law was “by definition” a civil offense when John Doe was arrested. See Appellant’s Br. 7.
. At oral argument the Does’ counsel conceded the 1997 law’s ambiguity, stating that whether it made underage possession a civil or criminal offense was not “crystal clear.” Oral Arg. at 44:02. The uncertainty could have been avoided if the D.C. Council had *468 simply added a subsection providing "Any person who is under 21 and possesses, purchases or consumes alcohol shall be subject only to civil penalties,” rather than lifting penalties from other subsections via cross-reference. It has done so in other statutes. See D.C.Code § 50-1401.Ol(d-l) (anyone who operates a motor vehicle in the District with a license expired for less than ninety days "shall be subject to a civil fine ... and shall not be subject to the criminal penalties contained in subsection (d) of this section”).
. The legislative history is, not surprisingly, inconclusive; the preamble to the 1997 law states that the intent was “[t]o amend the [ABC Act] to provide for criminal and civil penalties for misrepresentation of age or purchase, possession, or consumption of alcoholic beverages by persons under 21 years of age.” 43 D.C.Reg. 4515 (1996) (emphasis added).
. The District also argues that because the issue of whether the 1997 and 2001 laws authorized arrest for underage possession is an issue of unsettled state law, the
Pullman
abstention doctrine applies and supports affirming the dismissal.
Pullman
abstention "holds that 'when a federal constitutional claim is premised on an unsettled question of state law, the federal court should stay its hand in order to provide the state courts an opportunity to settle the underlying state-law question and thus avoid the possibility of unnecessarily deciding a constitutional question.’ ”
See JMM Corp. v. District of Columbia,
. We note that while we have the authority to affirm the dismissal of the Jane Does’ Fourth Amendment claim on the merits notwithstanding the district court dismissed for lack of jurisdiction,
see Flynt v. Rumsfeld,
In
United States v. Bookhardt,
