SUMMARY

August 15, 2019

2019COA126

No. 18CA0290, People v. Whisler — Crimes — Possession of 

Weapons by Previous Offenders; Affirmative Defenses —

Mistake of Law

A division of the court of appeals holds that a defendant 

charged with unlawful possession of a weapon by a previous 

offender (commonly referred to as POWPO) cannot raise the defense 

of mistake of law based on having passed a background check when 

purchasing a firearm.

The summaries of the Colorado Court of Appeals published opinions 

constitute no part of the opinion of the division but have been prepared by 

the division for the convenience of the reader. The summaries may not be 

cited or relied upon as they are not the official language of the division. 

Any discrepancy between the language in the summary and in the opinion 

should be resolved in favor of the language in the opinion.
COLORADO COURT OF APPEALS 2019COA126

Court of Appeals No. 18CA0290

Fremont County District Court No. 16CR724

Honorable Ramsey Lama, Judge

The People of the State of Colorado,

Plaintiff-Appellee,

v.

Curtis Edward Whisler,

Defendant-Appellant.

JUDGMENT AFFIRMED

Division IV

Opinion by JUDGE J. JONES

Román and Rothenberg*, JJ., concur

Announced August 15, 2019

Philip J. Weiser, Attorney General, Grant R. Fevurly, Assistant Attorney 

General, Denver, Colorado, for Plaintiff-Appellee

Mallika L. Magner, Alternate Defense Counsel, Crested Butte, Colorado, for 

Defendant-Appellant

*Sitting by assignment of the Chief Justice under provisions of Colo. Const. art. 

VI, § 5(3), and § 24-51-1105, C.R.S. 2018.
1

¶ 1 Defendant, Curtis Edward Whisler, appeals the judgment of 

conviction entered after the trial court found him guilty of 

possession of a weapon by a previous offender (POWPO). We affirm. 

In so doing, we reject Whisler’s contention that his testimony that 

he had passed two background checks when buying two of the guns 

at issue entitled him to assert the affirmative defense of mistake of 

law as to all of the weapons. 

I. Background

¶ 2 While executing a search warrant of Whisler’s home, a police 

officer found methamphetamine and four guns, all of which Whisler 

owned. Because Whisler had a prior felony conviction, the People 

charged him with a single count of POWPO. 

¶ 3 Before trial, Whisler endorsed the affirmative defense of 

mistake of law. He also waived his right to a jury. 

¶ 4 During the bench trial, a police officer testified that he found 

the following four firearms in Whisler’s home while executing a 

search warrant: a “Charles Day 12-gauge” shotgun, a “Marlin 22 

Magnum” rifle, a “410” shotgun, and a “22-caliber Ruger” pistol. 

The prosecutor introduced the guns into evidence. 
2

¶ 5 Whisler testified in his defense. He admitted that he had a 

prior felony conviction for attempted possession of a controlled 

substance. And he admitted that he had possessed the four guns. 

But he also testified that

• he bought the 12-gauge shotgun at a Walmart in Cañon 

City about ten to twelve years earlier after undergoing a 

background check; 

• he bought the rifle at a Walmart in Salida after 

undergoing a background check; 

• he bought one of the other two guns from a friend who, 

Whisler “imagine[d],” had “probably” conducted a 

background check; 

• he traded something (he didn’t remember what) to 

someone (he didn’t say who) for the fourth gun;

• he believed that he legally possessed all the weapons 

because he had passed background checks when he 

purchased two of them; and

• he was aware of his constitutional right to bear arms. 

¶ 6 At the close of the evidence, defense counsel argued that 

Whisler was entitled to the affirmative defense of mistake of law 
3

based on section 18-1-504(2)(b) and (c), C.R.S. 2018. Counsel 

reasoned that the Colorado Bureau of Investigation (CBI) was 

required to deny the transfer of a firearm if it violated state law and, 

because Whisler had purchased guns from two gun dealers which 

were required to conduct background checks for prior felony 

convictions and had passed those background checks, Whisler 

reasonably believed that the CBI had given him permission to 

possess them. 

¶ 7 The trial court rejected Whisler’s mistake of law defense, 

concluding that Whisler couldn’t assert it as a matter of law. It 

reasoned that, although Walmart and the CBI had the authority to 

approve the sale of a firearm, they did not have the authority to 

“grant permission for somebody convicted of a felony to possess a 

firearm” so, “even if the background check fail[ed] to reveal a felony 

conviction and . . . a subsequent sale occurs,” the possession of the 

firearm by the felon was not lawful. 

¶ 8 The court then found Whisler guilty of the POWPO count and 

sentenced him to eighteen months of probation. 
4

II. Mistake of Law

¶ 9 On appeal, Whisler reiterates his argument that he is entitled 

to the affirmative defense of mistake of law because the CBI gave 

him permission to possess all the guns when he passed background 

checks before purchasing two of them. His argument misses the 

mark.

A. Standard of Review and Applicable Law

¶ 10 We review de novo whether a defendant is entitled to assert a 

mistake of law defense. People v. Gutierrez-Vite, 2014 COA 159, 

¶ 11. 

¶ 11 “A mistake of law defense relates to the mistaken belief that 

conduct does not, as a matter of law, constitute a criminal offense.” 

People v. Lesslie, 24 P.3d 22, 25 (Colo. App. 2000). Generally, 

“ignorance of the law or mistake of law is no defense to criminal 

prosecution.” People v. Holmes, 959 P.2d 406, 414 (Colo. 1998). 

¶ 12 The General Assembly has codified this principle. Section 18-

1-504(2) says that mistake of law is not a defense “unless the 

conduct is permitted by” certain law, persons, or entities, and only 

then under specified circumstances. Whisler invokes two statutory 

exceptions. The first is that a person is relieved of criminal liability 
5

for conduct that is permitted by “[a]n administrative regulation, 

order, or grant of permission by a body or official authorized and 

empowered to make such order or grant the permission under the 

laws of the state of Colorado.” § 18-1-504(2)(b). The second is that 

conduct may be permitted by “[a]n official written interpretation of 

the statute or law relating to the offense, made or issued by a public 

servant, agency, or body legally charged or empowered with the 

responsibility of administering, enforcing, or interpreting a statute, 

ordinance, regulation, order, or law.” § 18-1-504(2)(c).

B. Analysis

¶ 13 We conclude that the trial court properly determined that 

neither of the statutory exceptions applies to Whisler, as a matter of 

law. 

¶ 14 Whisler didn’t present any evidence of an administrative 

regulation, order, or grant of permission by anyone authorized or 

empowered to give such permission that would have permitted him 

to possess firearms. The CBI serves as the state point of contact for 

the national instant criminal background check system and is 

required to deny a background check if the transfer of the firearm 

would violate any provision of state law. But in that role, the CBI 
6

doesn’t grant permission to violate the law; rather, it attempts to 

determine whether a person can legally possess a firearm based on 

the information available to it. See § 24-33.5-424(2), (3)(a), C.R.S. 

2018. 

¶ 15 And, even if passing a background check could be construed 

as a “grant of permission” by the CBI, that agency doesn’t have the 

authority to make an exception to the POWPO statute that would 

have allowed Whisler (or any other convicted felon) to possess a 

firearm. Whisler cites no authority for the proposition that the CBI 

has such authority, and we aren’t aware of any.

¶ 16 Likewise, Walmart, a private entity, didn’t have any authority 

to grant Whisler permission to possess a firearm in contravention of 

the law. See Rocky Mountain Gun Owners v. Hickenlooper, 2016 

COA 45M, ¶ 44 (a licensed gun dealer’s initiation of a background 

check “does not make [it] the principal agent of state enforcement 

charged with keeping firearms away from criminals”). 

¶ 17 As for subsection (2)(c) of section 18-1-504, Whisler didn’t 

present any evidence of an “official written interpretation of” the 

POWPO statute by anyone empowered to make such an 

interpretation giving him permission to possess firearms.
7

¶ 18 Under these circumstances, we conclude that Whisler wasn’t 

entitled to have the fact finder (in this case, the trial court) consider 

the affirmative defense of mistake of law. Cf. Lesslie, 24 P.3d at 24-

25 (the mistake of law defense didn’t apply because, even though 

the sheriff had directed the defendant to install an electronic 

listening device in the men’s restroom at a bar, “the sheriff was not 

an official authorized or empowered to permit the interception and 

recording of communications by such a device”).

¶ 19 In so concluding, we necessarily reject Whisler’s argument 

that his case is analogous to United States v. Brady, 710 F. Supp. 

290 (D. Colo. 1989). In Brady, the defendant was relieved of 

criminal liability for possessing a firearm as a convicted felon in 

violation of a federal statute because he had relied on the advice 

given to him by a state court judge that he could continue to use a 

firearm for hunting and trapping in his occupation. Id. at 291-92, 

296. The federal district court concluded that the defendant was 

entitled to rely on the advice of the judge because the judge had a 

constitutional duty to interpret and apply federal law. Id. at 295. 

In contrast, though the CBI is required to notify the seller if transfer 

of the firearm would violate state law, the CBI doesn’t have any 
8

authority or duty to interpret, apply, or grant exemptions from the 

POWPO statute. 

¶ 20 Whisler’s reliance on Cox v. Louisiana, 379 U.S. 559 (1965), 

Raley v. Ohio, 360 U.S. 423 (1959), and similar cases is also 

misplaced. Those cases, unlike this one, involved factual 

circumstances in which the alleged grant of authority came from a 

source that had the authority to permit the action. See Cox, 379 

U.S. at 569-71 (demonstrators acting with the permission of the 

police chief); Raley, 360 U.S. at 437-39 (witnesses acting upon the 

advisement of the chairman of the commission before whom they 

appeared).

III. Conclusion

¶ 21 The judgment is affirmed.

JUDGE ROMÁN and JUDGE ROTHENBERG concur.