On Election Day 2008, Maruse Heath, the leader of Philadelphia's New Black Panther Party, stood in front of a neighborhood polling place, dressed in a paramilitary uniform.

Within hours, an amateur video showing Heath, slapping a black nightstick and exchanging words with the videographer, had aired on TV and ricocheted across the nation.

Among those who saw the footage was J. Christian Adams, who was in his office in the Justice Department's Civil Rights Division in Washington.

"I thought, 'This is wrong, this is not supposed to happen in this country,' " Adams said. "There are armed men in front of a polling place, and I need to find out if they violated the law, because in my mind there's a good chance that they did."

The clash between the black nationalist and the white lawyer has mushroomed into a fierce debate over the government's enforcement of civil rights laws, a dispute that will be aired next week when the U.S. Commission on Civil Rights unveils findings from a year-long investigation.

Two months after Election Day, Adams and his supervisors in the George W. Bush administration filed a voter-intimidation lawsuit against Heath and his colleagues, even though no voters had complained. The Obama administration months later dismissed most of the case, even though the Panthers had not contested the charges.

Interviews and government documents reviewed by The Washington Post show that the case tapped into deep divisions within the Justice Department that persist today over whether the agency should focus on protecting historically oppressed minorities or enforce laws without regard to race.

The dispute over the Panthers, and the Justice Department's handling of it, was politicized from the start, documents and interviews show. On Election Day, the issue was driven by Republican poll watchers and officials and a conservative Web site.

At the department, Adams and his colleagues pushed a case that other career lawyers concluded had major evidentiary weaknesses. After the Obama administration took over, high-level political appointees relayed their thoughts on the case in a stream of internal e-mails in the days leading to the dismissal.

That decision to pull back the lawsuit caused conflicts so heated that trial team members at times threw memos in anger or cursed at supervisors.

The dismissals triggered outrage from conservatives and congressional Republicans, two internal Justice Department inquiries and the investigation by the conservative-controlled civil rights commission. The debate has thrust Eric H. Holder Jr., the nation's first African American attorney general and long the target of Republican attacks, into an unwelcome spotlight.

In recent months, Adams and a Justice Department colleague have said the case was dismissed because the department is reluctant to pursue cases against minorities accused of violating the voting rights of whites. Three other Justice Department lawyers, in recent interviews, gave the same description of the department's culture, which department officials strongly deny.