David Carrillo, executive director of the California Constitutional Center at UC Berkeley School of Law, said the president has broad powers when it comes to what he can and can't do via executive orders.

"President-elect Biden can require masks in federal buildings because, by executive order, he can regulate the operation of the federal government. But he probably can't require masks on interstate buses and trains because only the U.S. Congress can regulate interstate commerce by law, not the president by directive," Carrillo said.

Bill Dunlap, who teaches constitutional law at Quinnipiac University School of Law in Connecticut, said if a litigant brings a mask mandate to court, "which will undoubtedly happen," the courts will then "look to see what Congress has done and compare the president's rules with existing congressional rules to see whether they contradict each other or support each other."

The mask mandate concerning federal property is "probably within Mr. Biden's authority, but they will be challenged," Dunlap said, echoing Carrillo.

Many believe the issue certainly would make its way up to the U.S. Supreme Court. If the court takes up the matter, experts say, it's a whole new ballgame.

"What we see now is a Supreme Court in turmoil where the chief justice [John Roberts Jr.], who is conservative, has sided with the liberals on the court on matters of health and safety during the pandemic. We have seen, with [Justice] Ruth Bader Ginsburg no longer on the court, a reversal with Amy Coney Barrett [Ginsburg's replacement] in the early pandemic Supreme Court rulings," said Michelle Goodwin, a professor of law at the University of California, Irvine School of Law.

Goodwin, also a member of the university's Center for Biotechnology and Global Health Policy, said, "I'm deeply concerned that the Supreme Court is projecting partisanship. I'm concerned the perception of the court is one of being partisan and that this court lacks the commitment of following empirical, health-based evidence. There are significant worries with this particular court in protecting the health of Americans."

Hugh Murray III, a labor and employment attorney with McCarter & English in Hartford, has worked on various matters involving state and federal mandates covering a range of issues. He believes those challenging the mask mandate will be strategic.

"I think it could be a specific issue concerning someone's free exercise of religion and the refusal to wear a mask under certain limiting circumstances. If that is the case, the high court could rule against the government," Murray said.

Dunlap noted the Public Health Service Act and Centers for Disease Control and Prevention regulations can delegate "powers to the executive branch to take actions that are reasonably necessary to prevent the interstate spread of diseases if the local and state responses are inadequate. But the language is very vague and nobody has ever tried to impose these kinds of regulations before. No president has tried this before."

Dunlap said if he were advising the incoming president, "I'd tell him I would have no problem saying there's a strong argument that these regulations will allow you to issue these mandates."

Biden's attorneys, Dunlap said, could also point to a 1905 U.S. Supreme Court ruling to help make their case.

In Jacobson v. Massachusetts, the country's high court in 1905 ruled 7-2 that states may mandate public health regulations. The issue at the time was small pox vaccinations and, Dunlap said, "the Supreme Court said that while there is a right of privacy, under appropriate conditions, such as a public health emergency, states may mandate public health regulations."

Dunlap said it's important to note the distinction that Jacobson v. Massachusetts dealt with just one state, not the entire nation.

But, Dunlap said, "Biden's attorneys can use Jacobson to show that a mask mandate does not constitutionally infringe on an individual's rights."