Significant numbers of police officers officers across the country are refusing the COVID-19 vaccine, ignoring mandates and leaning on their unions to back them up.

Why it matters: The Fraternal Order of Police, a national police union that represents 356,000 officers, estimates that more than 500 officers have died from COVID since the pandemic began.

• The union and other police groups did not know of any statistics around how many believe to have contracted COVID on the job — or how many may have spread the virus.

The big picture: Cases have surged nationwide thanks to the Delta variant. Police are a major, omnipresent labor force tasked with protecting and interacting with the public.

• Like health care workers, teachers and the military, police officers' COVID status could have ripple effects.

Driving the news: Denver’s top public safety leader said last week he'll discipline police officers and sheriff’s deputies who ignore a mandate to get vaccinated. A Denver Police Protective Association survey found 57% of its members aren't vaccinated.

• A 10th employee of the Los Angeles Police Department died last week from complications of COVID-19 as the department saw 36 more cases, the Los Angeles Times reported. Half of the department remains unvaccinated.
• The San Francisco Deputy Sheriffs' Association promised that deputies would quit en masse or seek early retirement over San Francisco Mayor London Breed's new vaccine mandate for officers. The group says 160 out of 700 deputies are not vaccinated due to religious or other beliefs.
• In Michigan's Van Buren Township, west of Detroit, Adam Byrd, president of the local Police and Dispatchers Union, recently said perhaps one in five of the township's police and fire officials might quit as a result of a vaccine mandate.
• New York Mayor Bill de Blasio announced that by Sept. 13 "every single city employee will be expected to be either vaccinated or tested weekly. This means everybody...this means the NYPD." He promised "consequences" and to be "very tough if a city government employee does not wear a mask and they are unvaccinated."

The intrigue: The Fraternal Order of Police has said the science is clear about the safety of the COVID-19 vaccines and recommends its members get vaccinated.

Yes, but: "We are a union and we will defend our members," executive director Jim Pasco told Axios. "You cannot tell people what to do. It's still an individual and personal choice."

• Pasco denounced officials threatening officers with termination over defying vaccine mandates.
• Specifically, he called out Miami Police Chief Art Acevedo for telling unvaccinated officers to go work elsewhere: "That's management by tantrum. That's not going to work. Have a conversation and encourage officers, but don't act childish."

Between the lines: Employers have the right to mandate vaccinations as a condition of employment, legal scholars say.

• "Does the state generally have the power to impose vaccination requirements on workers? Historically, the answer has been yes," South Texas College of Law Houston constitutional law professor Josh Blackman told Axios.

But, but, but: Many police officers are represented by unions, and it would have been impossible for agreements to include mandates around COVID-19 vaccines before the pandemic, Blackman said.

• Such mandates could be in violation of collective bargaining agreements, he said. "Unions don't like to yield ground. They like to fight for every single benefit. So if they're suddenly giving up members' rights, then they're perhaps giving ground for some future collective bargaining battle."