The NY Times has more details on Judge Urbina's decision to drop charges against the Blackwater defendants, accused of murdering Iraqis in a 2007 ambush on a State Department convoy moving through downtown Baghdad:

The judge also blasted prosecutors for withholding "substantial exculpatory evidence" from the grand jury that indicted the defendants, as well as presenting "distorted versions" of witness testimony, and improperly telling the grand jury that some incriminating statements had been made by the defendants but were being withheld.

The prosecutorial team was led by Kenneth Kohl, an assistant United States attorney. The Justice Department declined to make him available for comment.

The judge's allegations of prosecutorial misconduct were the latest in several blows to federal prosecutors in 2009 in which judges dismissed high-profile cases and called the government's credibility into question.

Early in the year, for example, at the request of Attorney General Eric H. Holder Jr., a federal judge threw out the conviction of former Senator Ted Stevens, Republican of Alaska, for having failed to report gifts on his disclosure forms. Justice Department officials had uncovered evidence that prosecutors in that case had failed to turn over potentially exculpatory evidence to the defense, as required by law.

And last month, a federal judge threw out a major stock option back-dating case against top executives of the chip-maker Broadcom after finding that a prosecutor in that case had inappropriately pressured witnesses to testify in a manner favorable to prosecutors.