What do I do  if I was rear-ended by a police officer?

Your state provides insurance for police officers as state employees.  You should contact the police department to obtain the address and telephone number of the insurance carrier.  If you have trouble obtaining that information from the police department, contact the insurance commissioner for your state.  Since  police officers are state employees, you will probably be required to file a separate claim prior to filing a lawsuit against the police officer and police department.  That separate claim will probably be denied and then you can file your lawsuit for negligence against the police officer and police department.  You should also name the state as a defendant in your lawsuit as the police officer is a state employee.  Don't miss the deadline for filing the separate claim or you may lose your rights to proceed with the matter.