The fear of an Ebola outbreak in the United States, no matter how unlikely, has led authorities in some states to take the highly unusual step of requiring an entire category of people to be quarantined, regardless of the actual degree of risk they might pose to the public.

That situation has led Maine nurse Kaci Hickox to a potential showdown with state officials about whether she should be forced to be quarantined. Hickox previously was isolated in a special tent at University Hospital in New Jersey for four days after she returned home to the U.S. from treating Ebola patients overseas after New Jersey Gov. Chris Christie imposed a mandatory quarantine for anyone entering the state who had been in an Ebola-affected country.

Hickox, who worked in Sierra Leone with Doctors Without Borders, shows no symptoms of the potentially fatal disease, which is necessary to transmit it to others; but now Maine health officials say if she does not abide by the quarantine, they will seek a court order to enforce it.

The issue pushes to the forefront the tension between an individual’s civil rights and the public’s expectation that the government will do what it must to keep them safe.

“Normally one can’t be locked up without suspicion of a crime or conviction, but because infections are catching and because they can be spread by people who are not visibly sick, the state has the right to protect society from disastrous consequences by temporarily limiting someone’s liberties,” said Eugene Kontorovich, a constitutional law scholar at Northwestern University Law School in Chicago.

Health officials in the United States have a long history of taking steps in the interest of public health, including closing schools and imposing large-scale quarantines, such as the quarantine imposed during the influenza epidemic of 1918, which was credited with limiting the disease’s spread.

By contrast, a requirement that Chinese residents in San Francisco in 1900 be inoculated and quarantined after an outbreak of a plague was overturned by the courts as racist.

Courts generally have sided with the state in instances when civil liberties are pitted against public health, Kontorovich said.

Some public health experts say aggressive, widespread quarantines might be illegal if they are not based on medical evidence, and they can be counterproductive because they could lead people to hide their potential exposure or travel history. In the current environment, they also could dissuade health care workers from volunteering to fight Ebola in West Africa, where it is an epidemic threatening to spread beyond a few impoverished countries.

Quarantines also create unnecessary fear.

Arthur Caplan, founding director of the Division of Medical Ethics at New York University’s Langone Medical Center, said that by imposing a quarantine, even a voluntary one, it’s sending a message to the public that there’s something to fear when there isn’t.

“No state has made it clear how they would enforce a quarantine,” he said. “If she leaves the house, are they going to shoot her? Are they going to Taser her? Is there going to be a guard at her door dressed in a moon suit?”

Governors in New Jersey, New York and Illinois — all with international airports — announced policies last week that call for health care workers and others who have been in close proximity to people suffering from Ebola to remain in quarantine for 21 days, the maximum period it could take for someone infected with the disease to start showing symptoms.

Now several other states have announced measures that go beyond the recommendations of the federal Centers for Disease Control and Prevention, which says people should be monitored for symptoms but not confined.

The federal CDC also no longer uses the word “quarantine” in its Ebola protocols for people at risk. However, states have their own authority to take steps to protect public health.

“Public health law is all state-based, so where the balance (between civil liberties and public health) lies is all state-based,” said Amy Major, associate director of the Center for Health and Homeland Security at the University of Maryland.

“You have to have certain due process opportunities. You have to be able to challenge the order and appeal it,” Major said.

The situations that might trigger restrictions on people’s movements are written broadly so health officials can be responsive to each particular situation. Although it has a high mortality rate, Ebola is difficult to contract. Typhoid, by comparison, can be carried by someone who is not at all sick but can infect every person with whom he or she comes in contact.

Health officials also make a distinction between isolation, in which a sick person is allowed no contact with others, and quarantine, in which a person is potentially sick but it remains to be determined whether they will become sick. They are allowed contact with others.

Voluntary quarantine is a step that is much less demanding on the health infrastructure than isolating someone at a medical facility, and it also assures the patient’s basic needs are met, Major said. One of the primary objections to Hickox’s detention in New Jersey was the fact that she could not have access to anyone, did not have a television and had almost no comforts, such as a flush toilet.

“If you put someone in that limited movement restriction, you need to support their basic needs,” she said.

In Maine, state law allows the Department of Health and Human Services to confine a person “reasonably believed to have a communicable disease” but requires a court order.

“Upon the department’s submission of an affidavit showing by clear and convincing evidence that the person or property which is the subject of the petition requires immediate custody in order to avoid a clear and immediate public health threat, a judge of the District Court or justice of the Superior Court may grant temporary custody of the subject of the petition to the department and may order specific emergency care, treatment or evaluation,” the law says. The court can take measures it deems necessary for public safety pending a hearing on the petition.

Maine has used its power before. In 2006, the state obtained an arrest warrant for a 54-year-old homeless man with tuberculosis, a highly contagious airborne disease, because officials could not be sure he was taking his medicine to prevent the disease’s spread. The man had stopped once before and spread a drug-resistant form of the disease to three other people who were in close contact with him. He was held in jail until he could be transferred to a medical facility with a TB unit.

The Maine law seeks to balance a person’s civil rights with the general public welfare, but the state needs to establish a compelling case to deprive someone of their liberty, said Alison Beyea, executive director of the American Civil Liberties Union in Maine.

“Maine law allows for some restrictions to take place when we have an actual or threatened epidemic of disease. At this stage we’re not there. There’s no justification for mandatory quarantine at this point,” she said. “This is a medical issue, and we need to be guided by medical science and not by fear.”

But Kontorovich said the question of what steps to take to prevent the spread of disease is not strictly a medical one.

“Science could say what the potential risk is. The question is, how do you value that risk? Even if they say there’s very little chance, they can’t say how much that risk is worth and they can’t say how much the inconvenience (of quarantine) is worth,” Kontorovich said. “It’s not a science question. It’s a policy question,” one appropriately left to elected politicians, he said.

The current public mood appears to favor mandatory quarantines, driven in part by the lethality of the disease in Liberia, Sierra Leone and Guinea and its rapid spread through undeveloped areas there. More than 10,000 people have contracted the disease in West Africa and almost 5,000 have died, according to the federal CDC.

Public health officials, however, note that those countries lack the health infrastructure needed to help someone recover from the disease, techniques such as providing intravenous fluids to prevent dehydration and therapies to keep bodily organs working until the disease is under control. In Dallas, the second of two health care workers who contracted the disease while treating an Ebola patient from Liberia was released from the hospital Tuesday after testing negative for the disease.

The only fatality in the U.S. has been Thomas Duncan, who had contracted the disease in Liberia and was already ill when he reported to the hospital in Dallas.

Kontorovich believes the altruism of people helping fight the disease in Africa should make them willing to take public health concerns seriously at home.

“It’s very noble that people want to go to Africa and help treat people there,” he said. “Surely the thing to do is to extend that to taking the measures our elected government officials believe are suitable to prevent introduction of the disease to the United States.”

Staff writer Joe Lawlor contributed to this report.