Sometimes people require an expert witness
There are certain times that an individual or a company needs an expert witness to testify for a court case. I have been called upon several times for this and can easily be classified as an expert in the field of overhead glazing or skylights.
My policy for local (Denver, Colorado) cases is to charge for my time only if they win their case. It is my way of helping others out. Out of town trips would have to be billed as I would incur expenses, however, I still would work something out for my personal time, depending upon the circumstances.