In most cases, the plaintiff (the person who is suing) can choose to file the lawsuit in the state where the accident occurred, the state where the defendant (the person being sued) is domiciled, or the state where the plaintiff is domiciled.
For example, let's say that you were in a car accident in California, but you live in Arizona. You may be able to file a civil suit in California, Arizona, or the state where the defendant lives.
Before filing a lawsuit, it is important to consult with an attorney to determine the best jurisdiction for your case. An attorney can also help you understand the specific laws and procedures that apply to civil suits in the state where you wish to file the lawsuit.