It's not a "right", it's a reaction. And yes, by law, it's legal to cause an accident by avoiding another accident. There is a lot of negligence out there but taking it to the point of "everyone is liable for mistakes" is taking this society into a liberal sue-happy future. People should not have to be paranoid of lawsuits and prison time while driving because paranoyia can cause an accident too. Drive at your own risk, but yes, there are many situations where negligence applies.
Wrong again. Swerving to avoid debris, a deer, or anything in the road, does not give you the right to run into someone else. In other words, you may feel you are in the right, but you are not, and will be liable for any damages you cause by running into someone else in your maneuver to avoid hitting something.
Example: You're going down the highway and notice traffic is stopped in front of you. If you change lanes to avoid rear ending the stopped traffic in front of you, and you change lanes into someone else, you are not in the right, you are at fault and you will be held liable.
There is no law anywhere in this country that would allow you to do that, and not be liable.