The Justice Department’s decision to charge former presidential candidate John Edwards with campaign finance violations drew criticism from legal experts, including some former prosecutors, that the case was too aggressive.

In the months before the indictment, the Justice Department took flak from government watchdogs for dropping corruption investigations of members of Congress. They argued that the government was not aggressive enough, and gun-shy from the collapse of its case against the late senator Ted Stevens .

Prosecutors at the Justice Department’s Public Integrity Section, whose mission is to probe corruption in government, “are in a very difficult position,’’ said Peter Zeidenberg, a former Public Integrity prosecutor.

Zeidenberg, who has been critical of the Edwards case but praises the section’s work overall, added that “the public wants them to be fearless and take on tough cases. But if they don’t prosecute, they’re seen as timid and not having any guts.’’

The Edwards case poses the latest challenge for a section that was in crisis two years ago. Prosecutorial wrongdoing led Attorney General Eric H. Holder Jr. to ask a judge to drop the case against Stevens (R-Alaska). Lawyers inside and outside the department spoke of staff turnover and poor supervision. The section’s leadership was replaced.

Since January, Public Integrity prosecutors have won eight trials: those convicted include a former Virginia state delegate, the former majority leader of the Puerto Rican Senate and a former office manager for the late senator Edward M. Kennedy (D-Mass.) found guilty of stealing more than $75,000 in unauthorized bonuses.

Justice Department officials say morale is high and the section’s leadership has stabilized under Jack Smith, a former federal prosecutor in Brooklyn selected to lead Public Integrity last year. “I could not be more proud of Public Integrity and of what we’ve accomplished,’’ said Lanny A. Breuer, assistant attorney general for the department’s Criminal Division, who supervises Public Integrity. “There is no doubt in my mind that it’s a very dynamic place.’’

But that hasn’t stopped the criticism. Much of it has focused on the department’s decisions to drop without filing charges at least seven investigations of current and former members of Congress since President Obama took office. Sources familiar with the probes have said that several were derailed or slowed by members asserting privileges under the Constitution’s “speech or debate” clause, which shields legislative work from executive branch interference.

After Edwards was charged with using illegal campaign donations to conceal his mistress from voters, experts said the government’s legal theory was unprecedented and overly aggressive. Prosecutors say payments from political donors to support and shield the mistress, Rielle Hunter, constituted illegal campaign contributions.

Justice officials declined to comment on Edwards or other cases, but Breuer said that “every decision we make in a high-profile case will please some and frustrate others. We are not going to make our decisions based on that. We are going to prosecute cases based on the facts and the law.’’

Melanie Sloan, a former federal prosecutor and executive director of Citizens for Responsibility and Ethics in Washington, said Public Integrity “does not have a coherent prosecution strategy.’’ She has called the Edwards case “remarkably weak.”

Andrew Lourie, who headed Public Integrity during the George W. Bush administration, agreed that the Edwards case will be “tough” for prosecutors to win. But he said the section overall appears “to be doing the right thing and the right kinds of cases.’’

Created in 1976 as a post-Watergate reform, Public Integrity has drawn praise for its core of motivated prosecutors, many of whom come from elite law schools. Its alumni include Holder and Deputy Attorney General James M. Cole. The section handles numerous public corruption cases, sometimes in partnership with the U.S. attorney’s offices.

As Public Integrity’s 28 prosecutors have sought to move past the Stevens mess, some judges have been critical. A federal judge in April accused prosecutors of “ridiculous” conduct over delays in turning over FBI documents to defense attorneys in a corruption case in Alabama.

“This is supposed to be some elite group coming down from D.C,’’ said the judge, Wallace Capel Jr., according to the Associated Press. A failure to turn over material to the defense was also a key problem in the Stevens case.

Several days later, Capel denied defense requests to suppress key evidence, saying prosecutors had not “willfully” disobeyed his orders, and he has ruled in favor of the government on other motions. Twelve people, including four current and former state lawmakers, were charged in a bribery inquiry related to bingo legislation. Three have pleaded guilty; the rest are now on trial.

A federal judge in Washington took a different view of Public Integrity’s work in the case against Fraser C. Verrusio, a former U.S. House staffer who in February became the 20th person convicted in connection with the Jack Abramoff lobbying scandal. A jury found that he accepting an illegal all-expenses paid trip to the 2003 World Series.

U.S. District Judge Richard W. Roberts praised both sides for “boatloads” of “good lawyering,” according to a transcript. “You all are welcome back in my courtroom any time,” he said.