In this particular instance, they would be liable for the costs incurred by Teamsters Local 115, on the grounds that the lawsuit is frivilous. I stress that this motion has just been filed, and they have not yet been awarded those costs.
and why are they getting sued for $40,000?
Well, they aren't being sued for that, not yet, anyway. Judicial Watch had a falling out with Don and Teri Adams late last year (actually, after the Summmary Judgment arguments were presented, which the Teamsters ended up winning last month). Afterwards, Judicial Watch expressed a desire to collect $40,000 in costs that they claim were spent on Don and Teri's defense. (They initially claimed, $240,000, but the judge limited the claim to $40,000.)