Vaccine mandates are getting pushback. But they are legal, experts say.

President Joe Biden was well within his legal rights when he announced Thursday that federal workers will be required to be vaccinated against Covid-19 or abide by stringent testing protocols, experts say. But don’t expect the new rules to avoid court battles.

As coronavirus cases rise in the United States, and as vaccination rates have fallen from their daily peak in April of more than 3 million shots to an average of 622,000 doses, companies such as Facebook, Google and Lyft are requiring their employees to be vaccinated. Now, the government is doing the same, too.

On Monday, the Department of Veterans Affairs became the first federal agency to require all its medical facility employees to be vaccinated against Covid. California this week became the first state to require coronavirus vaccinations or regular testing for state employees and health care workers. Then, the president followed suit.

“The Administration will encourage employers across the private sector to follow this strong model,” the White House said Thursday. Under the new policy, the unvaccinated must wear masks, socially distance from other employees and visitors, get tested up to twice a week and be subject to travel restrictions.

The federal government employs roughly 4 million people around the country, and the total number is closer to 10 million when contract and grant workers are included.

“Governments are employers, just as private businesses are employers,” said Juliet Sorensen, a clinical professor at the Northwestern Pritzker School of Law. “Employers are permitted to mandate activities that further the public health — and that includes vaccination.”

When a government is acting as an employer, the rules fall under employment law. “Those standards apply whether the employer is public or private,” she said. It’s only when the government is acting sovereign that things get trickier.

There is precedent for these requirements too. Military members have long been required to get certain vaccinations based on where they are being deployed, said Eric Feldman, a professor at the University of Pennsylvania Carey Law School.

He said much of the uncertainty and threats of lawsuits stem from the fact that Covid vaccines are still under emergency use authorization by the Food and Drug Administration. Critics argue it’s illegal to mandate the shots while they remain authorized only for emergency use.

But in a July 6 memo, the Department of Justice’s Office of Legal Counsel shut that argument down.

“The OLC memo says this EUA status issue is a bit of a red herring,” Feldman said. Still, “if the vaccines had final approval by the FDA, we would probably be seeing significantly less legal conflict.”

Importantly, a vaccine mandate doesn’t legally mean a person can’t refuse the shot.

“It’s not compulsory in the sense of holding people down and shoving needles in their arms,” Feldman said. “Taking this vaccine is a condition of participating in this particular activity” — that activity can be working at your job, attending a play, taking public transit or eating in a restaurant. Refusal is perfectly fine, but can still come with legal consequences.

Part of why recent requirements from the federal government are drawing scrutiny is because the issue hasn’t come up much, he said.

Vaccine mandates have historically been governed by state law, which is why some see Biden’s new mandate as unusual. Employment law differs from state to state, as do the rules governing vaccination requirements and exemptions. In Montana, employers can’t mandate Covid vaccinations under a new state law, with the exception of nursing homes, long-term care facilities and assisted living facilities. In Indiana, a federal judge is allowing Indiana University to continue with its Covid vaccination requirement for all students and employees. In Texas, more than 150 employees at a Houston hospital system who refused to get vaccinated were fired or resigned after a judge upheld the hospital’s right to require the shots.

Feldman said the Houston ruling by the judge who was appointed by former President Donald Trump likely points to the direction most litigation on the subject will go.

In the meantime, expect more lawsuits.

The Associated Press contributed.