What you say is true, but you're omitting the fact that judges routinely order the accusing party in nuisance lawsuits to pay the defendant's costs. $50k is nothing to facebook in the long run, especially since they are quite likely to get it back, and may in fact be worth it to establish a clear precedent in such cases - if such a precedent does not exist already.<p>By caving they are in effect setting their own precedent that trademark holders can demand and will receive arbitrary URLs on their private web site. You would think that this outcome would be so bad for them that they'd gladly pay practically any amount to avoid it.<p>So no - I don't think there is any credible legal reasoning behind FB's decision on this one. I would expect it is an internal policy, probably combined in this case with money and/or advertising commits changing hands.