Lavon R. Kent, a Karuk Indian, appeals her conviction after a bench trial for unauthorized residential occupancy of national forest system land. Kent contends that the district court erred in holding that she had no individual aboriginal rights to occupy the land in question. She also contends, for the first time on appeal, (1) that she was entitled to occupy the land because the Department of the Interior had issued her a certificate of eligibility for an allotment in a national forest and because the relevant statute contemplated that an Indian would occupy the land before actually applying for an allotment, and (2) that the government breached its trust responsibility to her as an Indian by bringing criminal proceedings against her. For the reasons discussed below, we reverse.
BACKGROUND
In lieu of a trial, the matter was submitted to the district court on a set of stipulated facts. The stipulated facts include the following. Kent is a member of *278the federally recognized Karuk Indian Tribe. Monies had been set aside for taking the Karuk Tribe’s lands by the United States government. As a result of this and other acts by the government, the Karuk Tribe’s aboriginal title to the land at issue in this case was extinguished. The Karuk Tribe does not have a reservation. Kent moved onto a site at Sandy Bar Creek within the Klamath National Forest in February 1984, and has occupied and possessed that site since then. She has placed a trailer on the site, which she uses as her living quarters, and has planted a garden, which yields food for her sustenance. Kent excludes others from the site.
The United States Forest Service has not issued a special-use authorization to Kent. Nor has the Forest Service granted Kent or anyone else an allotment of land at Sandy Bar Creek. Kent, however, applied for and on June 18, 1982 received a certificate of eligibility from the Department of the Interior which certifies that she is a California Indian who is eligible to obtain an allotment of land in a national forest.
Kent’s great-grandmother lived at Sandy Bar Creek continuously until her death in 1870. From approximately 1870 to 1984, no blood relative of Kent lived at Sandy Bar Creek. Kent’s mother was born one mile from Sandy Bar Creek and lived there until 1939. Relatives of Kent have Indian allotments just west of Sandy Bar Creek. Every year “since time immemorial” Karuk Indians have traveled along a road immediately adjacent to where Kent resides on Sandy Bar Creek to participate in the Ka-ruk ceremony of Pikiyowish (World Renewal).
On September 4, 1987, the district court issued a decision finding Kent guilty of unauthorized residential occupancy in violation of 16 U.S.C. § 551 (1985) and 36 C.F.R. § 261.10(b) (1988).1 United States v. Kent, 679 F.Supp. 985 (E.D.Cal.1987). The district court subsequently sentenced Kent to a thirty-day jail term and ordered her to pay a $25.00 penalty assessment. The district court stayed its sentence pending appeal. Kent filed a timely appeal from her conviction on February 19, 1988.
DISCUSSION
Kent argues that the district court erred because its holding is based solely on the extinguishment of Kent’s tribal aboriginal rights and because it failed to consider whether she had individual aboriginal rights based on her occupancy of the land. The district court expressly held “that the defendant does not possess an aboriginal right — through either her heritage as a Ka-ruk Indian or her occupancy of the site in question — to use land in the Klamath National Forest for residential purposes.” Kent, 679 F.Supp. at 987 (emphasis added). The district court clearly did consider whether Kent had any individual aboriginal rights to occupy the site at Sandy Bar Creek and correctly held that any such rights had been extinguished. See United States v. Dann, 873 F.2d 1189 (9th Cir.1989) (individual aboriginal title exists only when Indian can show that she or her lineal ancestors continuously occupied site, as individuals, beginning before date land was withdrawn from entry). We therefore affirm the district court’s holding that Kent does not have any individual aboriginal rights to occupy the land at Sandy Bar Creek.
Kent also contends that she is authorized to occupy the land because her certificate of eligibility2 entitles her to ap*279ply for and receive an allotment of land in a national forest and because the Forest Allotment Act of 1910, 25 U.S.C. § 337 (1983),3 contemplates that an Indian will occupy the land before applying for an allotment.4 She argues that even though she is not automatically entitled to a site of her choice, the fact that she moved onto the land in question only after being certified eligible to receive an allotment of land within a national forest, coupled with the language of the allotment statute, shows that 36 C.F.R. § 261.10(b) does not apply to her situation.
The government argues that Kent is not eligible to receive an allotment of land in a national forest because, as the government interprets the Forest Allotment Act (25 U.S.C. § 337), only those Indians whose families have continuously occupied the site in question since passage of the Forest Allotment Act in 1910 are entitled to receive allotments of national forest system land. According to the government’s interpretation, Kent is not eligible to receive an allotment because her ancestors were not already occupying the site at Sandy Bar Creek upon passage of the Forest Allotment Act and because her family has not continuously occupied the land ever since.
The government also interprets the Forest Allotment Act to mean — the plain language of the statute notwithstanding — that occupancy of national forest system land before applying for an allotment is prohibited by 16 U.S.C. § 551 and 36 C.F.R. § 261.10(b) unless the Indian can trace continuous ancestral occupancy of the site back to 1910. Again, according to the government’s interpretation, because Kent cannot trace continuous familial occupancy of the site in question back to 1910, Kent may not occupy the land before receiving an allotment, even should she ultimately be entitled to one. The government makes these arguments even though the Forest Allotment Act and related regulations do not state that continuous occupancy is required and even though Kent has been certified eligible to receive an allotment of land in a national forest.
We need not reach the underlying questions whether Kent is eligible for an allotment or whether she is entitled to occupy the land before applying for an allotment because we find that the government failed to prove that Kent had the mens rea necessary to be found guilty of violating 36 C.F.R. § 261.10(b). We also find that because Kent had insufficient notice that her conduct might be unlawful, due process will not permit her conviction to stand.5
*280The information charging Kent with violating 16 U.S.C. § 551 and 36 C.F.R. § 261.10(b) alleged that Kent “did knowingly take possession of, occupy and otherwise use National Forest System lands for residential purposes without a special-use authorization, or as otherwise authorized by Federal law or regulation_” (Emphasis added.)6 The mens rea embodied in “knowingly” requires the government to prove as an element of the offense that Kent “voluntarily and intentionally and not by accident or mistake” engaged in the prohibited conduct. United States v. Jewell, 532 F.2d 697, 699 (9th Cir.) (en banc), cert. denied, 426 U.S. 951, 96 S.Ct. 3173, 49 L.Ed.2d 1188 (1976); 1 Devitt and Black-mar, Federal Jury Practice and Instructions, § 14.04 (3rd ed. 1977). In the present case, unresolved ambiguities (discussed below) in the law relating to allotments of national forest system land to Indians preclude a finding that Kent knew that her occupancy of the site at Sandy Bar Creek was not allowed by federal law.
Kent’s certificate of eligibility, issued by the Department of the Interior, states that she is eligible to receive an allotment of land in a national forest. The Forest Allotment Act, 25 U.S.C. § 337, states that the government is authorized to make allotments “to any Indian occupying, living on, or having improvements on land included within any national forest_” (Emphasis added.) The government argues that although Kent has a certificate of eligibility, she is not eligible to receive an allotment of land in a national forest. The government also argues that although the language of the Forest Allotment Act can be read to contemplate that an Indian will occupy the land before applying for an allotment, such prior occupancy is in fact illegal. But the certificate of eligibility and the Forest Allotment Act, on their face, contradict the government’s contentions.
No reported cases have interpreted section 337 to determine which Indians are in fact entitled to an allotment or whether occupancy before applying for an allotment is allowed or required by the statute. These are open questions. Given the current unsettled state of the law and the information available to Kent, we find that Kent could reasonably believe that she was permitted by federal law to settle on the land at Sandy Bar Creek. The stipulated facts in this case and the government’s unsupported interpretation of the applicable laws cannot sustain a finding beyond a reasonable doubt that Kent had the requisite mens rea to be convicted of unauthorized residential occupancy of national forest system land.7
In supplemental briefing, the government argues that 36 C.F.R. § 261.10(b) sets forth a strict liability offense, despite the fact that the information alleged that the offense was “knowingly” committed. The government bases its argument on the lack of an explicit mens rea requirement in section 261.10(b). But more than omission of a mens rea requirement from the definition of an offense is necessary to justify dispensing with an intent requirement. United States v. United States Gypsum Co., 438 U.S. 422, 438, 98 S.Ct. 2864, 2874, 57 L.Ed.2d 854 (1978).
To avoid a construction of the regulation which would “criminalize a broad range of apparently innocent conduct,” Liparota v. United States, 471 U.S. 419, 426, 105 S.Ct. 2084, 2088, 85 L.Ed.2d 434 (1984), we interpret section 261.10(b) to “require[ ] a showing that the defendant knew [her] conduct to be unauthorized” by the regulation. Id. at 426, 105 S.Ct. at 2088. See also United States v. Nofziger, 878 F.2d 442, 454 (D.C.Cir.) cert. denied, — U.S. -, 110 S.Ct. *281564, 107 L.Ed.2d 559 (1989) (interpreting an ambiguous subsection of the Ethics in Government Act as requiring the government to demonstrate that the defendant had knowledge of the facts that made his conduct criminal).
We also reject the government’s argument that section 261.10(b) requires application of a strict liability standard because it is a “public welfare offense,” i.e., one which renders criminal “a type of conduct that a reasonable person should know is subject to stringent public regulation,” because the conduct “seriously threatens] the community’s health or safety.” Liparota, 471 U.S. at 433, 105 S.Ct. at 2092. Occupation of Forest Service lands is not an inherently dangerous activity, and the government has not submitted any evidence that Kent’s occupancy endangered the public.
In addition, we find that the relevant statutes and regulations did not give Kent sufficient notice that her occupancy of the site in question could be illegal. Due process requires that a penal statute give fair warning of what the law “commands or forbids.” Lanzetta v. New Jersey, 306 U.S. 451, 453, 59 S.Ct. 618, 619, 83 L.Ed. 888 (1939). Cf. Dunn v. United States, 442 U.S. 100, 112, 99 S.Ct. 2190, 2197, 60 L.Ed.2d 743 (1979) (where Supreme Court discussed its “long-established practice of resolving questions concerning the ambit of a criminal statute in favor of lenity. This practice reflects not merely a convenient maxim of statutory construction. Rather, it is rooted in fundamental principles of due process which mandate that no individual be forced to speculate, at peril of indictment, whether his conduct is prohibited ”) (citations omitted) (emphasis added); United States v. Sherbondy, 865 F.2d 996, 1009 (9th Cir.1988) (rule of lenity requires that where language of penal statute admits of more than one interpretation, courts should choose least harsh construction).
36 C.F.R. § 261.10(b) in clear language exempts anyone “otherwise authorized under Federal law” from the prohibition against occupying national forest land for residential purposes. As discussed above, this exception could reasonably be understood to apply to Kent. She has a certificate of eligibility which states that she is eligible for an allotment of land in a national forest and she has settled on the land pursuant to the plain language of the Forest Allotment Act which states that the government is authorized to make allotments “to any Indian occupying, living on, or having improvements on land included within any national forest....”
Neither the allotment statute nor the corresponding regulations state that there is a time limit within which an Indian must apply for- an allotment after receiving a certificate of eligibility. Nor do they state that continuous ancestral occupancy of the site since 1910 is required before an Indian is eligible to receive an allotment of land in a national forest. We find that the confused and contradictory information available to Kent, statutory and otherwise, failed to provide her with sufficient notice that her conduct might be criminally unlawful. Therefore, her occupancy of Sandy Bar Creek cannot be used as the basis for a criminal prosecution under 16 U.S.C. § 551 and 36 C.F.R. § 261.10(b).
The underlying questions regarding the rights conferred by Kent’s certificate of eligibility and the meaning of the Forest Allotment Act should be resolved before Kent can be held criminally responsible for unauthorized residential occupancy. The present criminal prosecution is basically the result of a land dispute between Kent and the Forest Service. Such a dispute can be adjudicated as a civil matter, where the meaning of the relevant statutes and regulations can be fully examined and where Kent’s ultimate right to occupy the land can be determined.8 If Kent now applies *282for an allotment, the issue can be resolved through those proceedings. Alternatively, if she fails to apply for an allotment, the government can bring a civil action that will lead to a proper resolution of the underlying land dispute. See, e.g., United States v. Hells Canyon Guide Service, Inc., 660 F.2d 735 (9th Cir.1981) (affirming district court’s order permanently enjoining defendant’s operation of boat service on river within national forest without a permit).
REVERSED.
. 16 U.S.C. § 551 requires the Secretary of Agriculture to regulate the occupancy and use of national forests, and further provides that violation of the Secretary’s regulations shall be punished by a fine of not more than $500 or imprisonment for not more than six months, or both.
36 C.F.R. § 261.10(b) states:
The following are prohibited:
(b) Taking possession of, occupying, or otherwise using National Forest System lands for residential purposes without a special-use authorization, or as otherwise authorized by Federal law or regulation.
. Kent's certificate of eligibility, dated June 18, 1982, provides in pertinent part: "This is to certify that Lavon R. Kent ... a California Indian, born May 6, 1947, is eligible as. an Indian to receive land ... in a national forest under Section 31 of the Act of June 25, 1910 [the Forest Allotment Act].”
. 25 U.S.C. § 337, states in pertinent part:
The Secretary of the Interior is authorized, in his discretion, to make allotments within the national forests in conformity with the general allotment laws, to any Indian occupying, living on, or having improvements on land included within any such national forest who is not entitled to an allotment on any existing Indian reservation, or for whose tribe no reservation has been provided.... All applications for allotments under the provisions of this section shall be submitted to the Secretary of Agriculture who shall determine whether the lands applied for are more valuable for agricultural or grazing purposes than for the timber found thereon; and if it be found that the lands applied for are more valuable for agricultural or grazing purposes, then the Secretary of the Interior shall cause allotment to be made as herein provided.
(Emphasis added).
. "The matter of what questions may be taken up and resolved for the first time on appeal is one left primarily to the discretion of the courts of appeals, to be exercised on the facts of individual cases.” Singleton v. Wulff, 428 U.S. 106, 121, 96 S.Ct. 2868, 2877, 49 L.Ed.2d 826 (1976). To "prevent a miscarriage of justice," United States v. Greger, 716 F.2d 1275, 1277 (9th Cir.1983), cert. denied, 465 U.S. 1007, 104 S.Ct. 1002, 79 L.Ed.2d 234 (1984), we exercise our discretion in this case to address whether the government's issuance of Kent’s certificate of eligibility or the language of the Forest Allotment Act require reversal of Kent’s conviction for unauthorized residential occupancy of forest system land.
.Kent also contends that the government breached its trust responsibility to her as an Indian by initiating a criminal action against her. In light of our findings (1) that the government failed to show that Kent possessed the requisite mens rea and (2) that Kent did not have sufficient notice that her occupancy of national forest system land might be illegal and subject her to punishment for unauthorized residential occupancy, we need not address this contention.
. The information thus specified the element of criminal intent that was not supplied by 36 C.F.R. § 261.10(b). See United States v. Morrison, 536 F.2d 286, 288 (9th Cir.1976) (indictment must specify intent if statute fails to do so).
. The government has published proposed regulations in the Federal Register which state that an Indian may not occupy the land before receiving an allotment. 52 Fed.Reg. 119, 23475 (1987) (to be codified at 36 C.F.R. pt. 254) (proposed June 27, 1987). These proposed regulations, published nearly one year after Kent's arrest, have not been adopted.
. The government indicated at oral argument that it knew of no other reported case in which an Indian has been criminally prosecuted for violating 36 C.F.R. § 261.10(b). Given this history, one wonders why the government should choose to institute criminal proceedings in this *282case, especially since less drastic civil measures were available. See United States v. Langley, 587 F.Supp. 1258, 1265 (E.D.Cal.1984) (Forest Service regulations may be enforced by injunction, as well as by criminal action).