Regarding the nurse that is refusing to submit to quarantine for Ebola, much ado is being made of the fact that she has tested negative for Ebola, and many are saying that since she has tested negative, this means that she isn't infected, and that placing her in quarantine is in opposition to science and to her rights.
First, the test. A test for Ebola (and most other infections) is based not on testing for the virus itself, but looking for the body's response to the virus. That is, when you are infected, your immune system eventually recognizes the infection and begins to produce chemicals to fight the infection. These chemicals are called antibodies. Each antibody is specific to the virus or other pathogen that it is being made in response to. When the levels of those antibodies rise to detectable levels, a person will show as "positive" for that infection. This is called "seroconversion" and is an indicator that you have been exposed to a given pathogen at some time in the past.
A negative test does not mean that you are not infected. It doesn't mean that you have never been exposed. All it means is that your body has not yet begin to produce antibodies. Some people take longer to develop detectable antibodies than others, and still others never develop them. (Called silent seroconversion) For example, I have been exposed multiple times to chicken pox (vaccination and direct exposure) and still have no detectable antibodies, but I have never caught the illness.
As to her rights, any person who is engaged in an activity that is dangerous to the health of others can result in restrictions. For example, I could say that it should be permissible for me to have a campfire in the living room of my first floor condo. After all, if the fire hasn't spread to an adjoining apartment, it isn't hurting anyone, right? How about being able to fire my pistol down a crowded street? After all, if no bullet strikes anyone, no one was harmed. Drunk driving?
In short, that argument doesn't fly with me. 21 days is not that big of a deal, and this nurse is acting like it is the end of the world.
(to my biology friends: I know that some of the concepts in here are oversimplified, but that doesn't change the gist of the argument.)