Norman Siegel, a civil rights lawyer, said Kaci Hickox's isolation upon her return from West Africa raised "serious constitutional and civil liberties issues," given that she shows no Ebola symptoms and has not tested positive for the disease.
"We're not going to dispute that the government has, under certain circumstances, the right to issue a quarantine," said Siegel, who was on his way to visit Hickox in a New Jersey hospital. "The policy is overly broad when applied to her."
The lawsuit would be the first to challenge the 21-day mandatory quarantine imposed by New Jersey for anyone arriving with a high risk of having contracted Ebola from Sierra Leone, Liberia and Guinea, where the epidemic has killed nearly 5,000 people.
The case could also affect similar policies announced by other states including New York and Illinois.
The lawsuit will argue that Hickox's constitutional right to due process was violated when she was forced into isolation, Siegel said.
State officials implemented a blanket policy without identifying a rational basis for confining asymptomatic individuals like Hickox, he said.
"The case law makes clear that the policy should be driven by medical fact, not fear," he said.
Michelle Mello, professor of law and public health at Harvard University, said courts in such cases seek to balance the level of danger posed by the disease with the likelihood that the individual poses a public threat.
But she said courts have found reason to uphold past quarantines, even when there was no definitive proof the individuals were ill.
"I don't think it is clear, but I suspect when all is said and done, it won't be successful," she said.
Lawrence Gostin, a Georgetown University law professor and health expert, said states' authority to issue quarantine orders is broad, but not unlimited.
"I can't recall a case in the 20th century where certain states are preparing to quarantine an entire class of people irrespective of their individualized risk," he said. "It just flies in the face of science, ethics and law."
In such cases, courts typically seek the least restrictive alternative, Gostin said, which might include voluntary confinement with monitoring. He said other quarantines, such as for drug-resistant tuberculosis, require a positive test.
Gostin has been in contact with Hickox via email to offer advice and support, he said.
Hickox, the first person isolated under the new orders, arrived on Friday at Newark Liberty International Airport in New Jersey after working with Ebola patients in Sierra Leone.
In an interview with CNN on Sunday, Hickox criticized the policy, saying she is "completely healthy."
But New Jersey Governor Chris Christie told Fox News on Sunday he would not back down. "This is government's job ... to protect the safety and health of our citizens."
The White House, worried that the quarantine orders could impede the fight against Ebola, has voiced its concerns to the governors of New Jersey, New York and other states, a senior administration official said on Sunday.