My wife was killed in an automobile wreck. She was alone in the car. The other driver says the wreck was her fault, but I don’t believe it. How can I prove what happened?
You need the help of an experienced automobile wreck attorney to lead an investigation into what happened.
Tennessee law provides that, because your wife is not able to testify about what happened, she is presumed to have been exercising due care at the time of the wreck. However, other testimony and evidence can make that presumption disappear.
Tennessee Injury Law Center

