Greetings!
Witnesses have lost many cases but of course have a good record too. Not surprising for the reactionist times, Witnesses initially lost the Gobitis flag salute case (http://caselaw.lp.findlaw.com/cgi-bin/getcase.pl?court=us&vol=310&invol=586) before it was overturned by the Barnette decision.
Probably the most famous loss though is the Chaplinsky case referred to in Gary Buss. This case set forth the famous "Fighting Words" area of restriction on free speech. (http://www.firstamendmentcenter.org/Speech/arts/topic.aspx?topic=fighting_words)
Although the case has never been officially reversed by the Sup. Ct. it is quite obvious in our society that either such laws restricting insulting each other are not in effect or they are not enforced. (except by bulletin board owners :--)
No cases follow Chaplinsky and there has never been a case that I know of that tried to use it as a basis for prosecution.
Although, I believe that the Chaplinsky case was wrongly decided and like the Gobitis case above, was a product of the hyper-patriotic anti-Witness times, it is too bad because it would be nice if it was against law to insult people. But the law of the time and the case is a bad one, people should be free to provoke a punch in the nose or to call the cops fascists or pigs if they want to. (not that I would)
If you look at the case facts you see very clearly that Chaplinsky was clearly having his constitutional rights and freedom of religion violated by the police officer. Unfortunatley, rather than politely standing up for his rights he used a poor choice of words. The words "damned fascist, mild to our modern ears, was deemed offensive to the patriotic community, but frankly, they accurately described the cop's behavior.
Anyway, Witnesses have lost other cases as an org and of course as individuals they have lost some legal cases and procedures having to do with child custody and medical decisions/no blood decisions.
-Eduardo Leaton Jr., Esq.