if you simply testified as an eye-witness, and claim that you heard these comments yourself - it is not slander or defamation - it is simply your own opinion.
slander lawsuits are threatened often - and rarely ever amount to anything.
speak the truth if you know it...
although...i at times lack "political correctness" - and the use of the word retard is not exclusively applied to people. look it up in the dictionary.
i find it hard to believe he would mean such remarks in a hateful way if his own brother had disabilities.
as for the racist jokes.......well.......that is digusting. i do not care if you like racist jokes and laugh at them/tell them - but such behavior is not compatible with having a seat on the school board.
if what you say is true - i must agree that he is probably not the best candidate to be on the school board.