By Allan Lengel

WASHINGTON — A federal judge here dropped charges against five Blackwater guards because of questionable prosecution tactics on the very last day of the year. It surely wasn’t the way the Justice Department wanted to wrap up 2009, a year that had a lot of ups and downs in the court.

The Justice Department scored some major victories in 2009 with the conviction of ex-Congressman William Jefferson and guilty pleas from the two Bernies — swindler Bernie Madoff and ex-New York Police Commissioner Bernie Kerik.

But the Justice Department  was embarrassed after a conviction of ex-Senator Ted Stevens was thrown out because of prosecutor misconduct and after a mistrial was declared for the fourth time in trial of John Gotti Jr. case when the jury was declared deadlocked.

On Thursday, in the Blackwater case,  U.S. District Judge Ricardo Urbina dismissed the charges against five guards accused of killing 14 unarmed Iraqi civilians in a crowded Baghdad traffic circle in 2007,  saying in a 90-page opinion that the Justice Department had wrongfully used “immunized statements” the men made to the State Department even though the men were told the remarks could not be used against them in court.