In her investigation, Ms. Dannehy appeared to draw a legal distinction between firing Mr. Iglesias for political reasons, which she said violated Justice Department principles, and doing so to influence an investigation that could harm Democrats, which would be illegal.

There was “insufficient evidence” that anyone in the White House or the Justice Department sought to pressure Mr. Iglesias to bring a criminal case before the 2006 election, nor was there evidence that the Justice Department tried to fill his spot with a prosecutor who would be more inclined to bring a political prosecution, the Justice Department said in its summary of Ms. Dannehy’s investigation.

“The weight of the evidence established not an attempt to influence but rather an attempt to remove David Iglesias from office, in other words, to eliminate the possibility of any future action or inaction by him,” the Justice Department summary said.

Representative John M. Conyers Jr., the Michigan Democrat who leads the House Judiciary Committee and was one of the Bush administration’s fiercest critics over the firings, said the decision should not be seen as an exoneration.

“There is no dispute that these firings were totally improper and that misleading testimony was given to Congress in an effort to cover them up,” he said.

But Mr. Gonzales’s lawyer in the case, George Terwilliger, said the decision amounted to a vindication and called it “long overdue.”

He said that Mr. Gonzales, who is now teaching at Texas Tech, “is pleased to be able to move ahead with his professional life” and added that “those who made unwarranted allegations and predicted a prosecution owe Judge Gonzales an apology.”