The U.S. has all but closed its borders in the fight against the coronavirus, but some state and local governments are going a step further by imposing travel restrictions on fellow Americans.

A handful of states have implemented mandatory quarantines for any visitors, while other localities have sought to turn around drivers whose travel they deem nonessential.

The moves are fraught with political and constitutional concerns, and some experts say there don’t appear to be any clear-cut public health benefits from the restrictions.

Health experts in particular have dismissed state travel measures as ineffective, describing them as too late, too broad and a drain on resources that could be better used on effective mitigation measures.

"There's definitely a lot more performing than performance," said Scott Burris, a professor at Temple Law School, where he directs the Center for Public Health Law Research. "You have to follow the data, rely on what we know from past experience and what we're learning here, and toss out everything else. Travel restrictions just don't fit into the smart way."

Such policies, health experts say, don’t take into account truck drivers, airline workers, people transporting necessary supplies and equipment or those who just slip across state lines.

“In the United States, there's so much interstate change, so much movement, that you can't possibly deal with it by interstate quarantine,” said Lawrence Gostin, a law professor who directs Georgetown University’s global health law center.

A smarter way, Gostin said, is for state officials to evaluate visitors on a case by case basis rather than implementing blanket travel restrictions.

“I think that the simple idea that just because you come from another state that you're a risk to others is invalid scientifically,” said Gostin. “You'd have to do an individual risk assessment to see whether or not they actually are at risk.”

But domestic travel restrictions gained traction earlier in the pandemic when they were openly discussed by top officials.

Anthony Fauci, the nation’s top infectious disease expert and a member of the White House coronavirus task force, told CBS News in early April that health officials were discussing the idea of such restrictions, while adding that no decisions had been made.

Legal experts say while the federal government has the power to regulate interstate commerce, states have broad authority to regulate intrastate travel and put in place certain emergency restrictions during a public health crisis.

But there are limits to that authority.

Since the U.S. Constitution guarantees the right to interstate travel, a state cannot fully block people from traveling over their borders. And while states can mandate quarantines for visitors, they must be careful such measures don’t veer into discrimination.

Earlier on in the coronavirus pandemic, Rhode Island became one of the first states to consider a ban on out-of-state travelers. Gov. Gina Raimondo (D) considered blocking vehicles with New York license plates from entering the state at a time when New York City’s coronavirus cases were skyrocketing.

New York Gov. Andrew Cuomo (D) responded by threatening a lawsuit if she implemented the proposal.

Raimondo instead chose to broaden the policy by requiring anyone to self-quarantine for two weeks upon arrival.

That move, legal experts say, allowed Rhode Island to avoid a discrimination challenge because it applied the health measures more generally, including Rhode Islanders coming back into the state.

Gillian Metzger, a constitutional law professor at Columbia University, said states must balance decisions to protect public health without discriminating against one another, adding that restrictions like stay-at-home orders are on safe legal ground.

"I think it's going to be very hard, particularly against the background of pandemic and of historic police powers, to come in and say that a stay-at-home order is unduly burdensome on interstate commerce in a way that's unconstitutional,” said Metzger.

She also noted that if states start to reopen their economies and choose to keep the travel restrictions in place, they are likely also going to find themselves on shaky legal footing.

“If what states are doing is saying, ‘We're going to have commerce inside, but you can't come from out of state and be part of it,’ then that's going to be problematic. That's discrimination,” she said.

But even as some states begin to reopen their economies, some travel restrictions have remained in place.

Alaska Gov. Mike Dunleavy (R) announced last week that the state will begin to open certain parts of its economy — like barbershops and nail salons — but international and out-of-state travel restrictions are set to remain in place until May 19.

Alaska, Hawaii and Florida were among the earliest states to announce restrictions.

In March, Florida Gov. Ron DeSantis (R), a staunch Trump supporter, signed an executive order with a 14-day quarantine requirement in place for certain visitors.

Under the order, DeSantis first required that anyone arriving from New York, New Jersey or Connecticut to self-isolate for two weeks. He later extended the order to include Louisiana when New Orleans emerged as a hot spot. The order excluded those who are employed by airlines as well as those providing a military, emergency or health response to the virus.

The order, which has a criminal penalty if violated, is set to expire next week, a few days after the economy is set to begin reopening.

Overall, while some health experts argue such restrictions are not effective, they also say it is not a good time for individuals in hot spot areas to be traveling.

And as more states move to reopen, experts say governors are recognizing the need to work together.

"For their own reasons, states are going to be more likely to want to collaborate and come up with agreements about reopening rather than trying to target their outside neighbors with measures that are less likely to be effective and really help them open up in a sensible way,” Metzger said.