When Nike went before the WIPO to get the transfer of justdoit.net, it lost.
Nike then appealed the decision before a federal district court in Illinois. This court ruled that the registrant's claim that he has used the phrase "Just Do It" for over 30 years in his motivational speaking business was insufficient to excuse his use of Nike's
trademark as a domain name. The registrant provided no evidence, beyond his own testimony, documenting his usage of the phrase. The court held that the registrant's unsupported contentions were insufficient to trigger the safe harbor of the ACPA.
[Nike Inc. v. Circle Group Internet Inc, Decided May 21, 2004 - U.S. Dist. LEXIS 9341]