As Denver takes steps to restrict federal agents conducting immigration enforcement in the Mile High City, its police chief said he is unclear as to how two new measures would be enforced.

“I don’t know, to be honest with you. I don’t know what that (enforcement) looks like,” Denver Police Chief Ron Thomas told The Gazette. “You know, fundamentally, I agree that they (federal immigration agents) shouldn’t be wearing masks when they engage in the way that they do. But what enforcement looks like, I’m not exactly sure.”

Thomas was referring to two actions the city is pursuing amid stepped-up enforcement of immigration laws in America’s interior cities. The federal operations in Denver have been so far limited compared to actions in other parts of the country, such as in Illinois and Minnesota.

The first, an ordinance, bans the wearing of face masks for all law enforcement officers, including federal immigration officers, when arresting and detaining individuals in Denver.

The second, an executive order from Denver Mayor Mike Johnston, prohibits U.S. Immigration and Customs Enforcement agents from conducting immigration enforcement on city-owned property and authorizes Denver police to intervene and even detain federal officers when observing the use of “excessive force.”

Although the new ordinance and executive order are officially on the books, Denver police and city officials are scrambling to figure out how to enforce them.

In Denver, the city’s legislative branch, the City Council, passes laws, which are subject to the mayor’s signature or, in some cases, a veto.

It is then up to city officials to implement the laws and to the courts to interpret them and determine whether they are correctly applied if lawsuits are filed.

Thomas, the police chief, said he does not know yet how the measures will be enforced and a Denver police spokesperson confirmed that the department is currently working with the City Attorney’s Office and the Mayor’s Office to determine what implementation of Johnston’s executive order would look like.

The spokesperson said that the agency plans to conduct additional training for officers “to ensure clarity on expectations.”

U.S. Immigration and Customs Enforcement officials pushed back against Johnston’s executive order, saying in a statement that local officials cannot prohibit federal agents from operating on public properties, calling it “legally illiterate,” and adding that “no local official has the authority to bar ICE from carrying out federal law on public property.”

Denver City Attorney Miko Brown disagrees.

“There is a menu of legal options that we could take depending on the circumstances,” Brown said of enforcing the executive order. “That could range from a civil penalty. It could also result in a criminal charge or it could result, for instance, in the city attorney asking a court to issue an injunction to prohibit that conduct.”

As for the mask ban, supporters said it helps protect the rights of immigrants, address public safety fears, and increase transparency. Others have warned of complications arising from local police confronting federal agents wearing masks while conducting operations in Denver.

De-escalation will be prioritized, and enforcement will be situation-dependent, a spokesperson from Johnston’s office said.

Thomas said part of the challenge his department faces is that local law enforcement must still maintain working relationships with federal agents on matters other than non-criminal immigration enforcement.

Both Denver and Colorado have long adopted “sanctuary” policies, which refer to laws or ordinances that limit or prohibit cooperation with federal immigration authorities.

“We do partner with federal law enforcement agencies,” Thomas said. “We are part of task forces that engage in investigations related to violent crime, human trafficking, guns, drugs, those kinds of things. And so, we want to continue those partnerships.”

Thomas added: “When it relates to federal immigration enforcement, we don’t want to take part in that. We don’t provide any assistance in that manner, and that won’t be joint operations, and (we) won’t be informing them.”

Denver is not the first jurisdiction to consider such measures in light of recent high-profile federal immigration enforcement operations.

California became the first state to ban most law enforcement officers, including federal immigration agents, from covering their faces while conducting official business under a bill signed in September by Gov. Gavin Newsom and criticized by Trump administration officials.

A federal judge has struck down the California law, saying it does not apply equally to all law enforcement officers and “unlawfully discriminates against federal officers.”