Award of fees to deft upon dismissal with prejudice following plaintiffs' mistaken motion to unilaterally dismiss a suit that had advanced past discovery and answer was not an abuse of discretion; plaintiff's lack of investigation, combined with their practices in other districts presented a sufficiently extraordinary circumstance to justify the grant.
http://www2.ca3.uscourts.gov/opinarch/172183p.pdf
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.