Rep. John Murtha, who last year called for the immediate pullout of U.S. troops from Iraq, this week accused an entire Marine company of murdering 15 Iraqis "in cold blood." Mr. Murtha claims he received his information from sources inside the Pentagon, which is conducting an investigation into the Nov. 15 incident in the town of Haditha. That investigation is not yet completed, which makes Mr. Murtha's accusation not only irresponsible, but an egregious violation of ethical conduct by a sitting congressman. Mr. Murtha concedes that he has not read any part of the Pentagon's unfinished report. All he has...