“The Justice Department is sending a clear message: that we will not accept criminal justice procedures that have discriminatory effects,” former Attorney General Eric H. Holder Jr. said in February after filing documents in a case involving high court bonds in Alabama. “We will not hesitate to fight institutionalized injustice wherever it is found.”

Loretta E. Lynch, who became attorney general in April, has continued the initiative unabated.

Civil rights groups have applauded the move — and in turn flooded the Justice Department with requests for government intervention in their cases. But to lawyers on the other side, it can feel as if the government is using private court cases to make political points.

“From the community’s perspective, it was an ongoing nightmare,” said Scott G. Thomas, the lawyer for Burlington in the lawsuit over legal aid. The Obama administration’s involvement turned the city of about 8,000 people into a national symbol. “Why is the Department of Justice interested in a little case involving two little communities in northwest Washington?” Mr. Thomas said.

Federal law allows the attorney general to argue on behalf of the government’s interest in any court in the country. Often, that means stepping in when foreign policy or national security are at issue. Under President George W. Bush, for example, the Justice Department weighed in on a lawsuit by victims of terrorism who were trying to seize valuable Iranian antiquities held by American museums. The administration urged a judge to “exercise circumspection in light of the potential foreign policy implications” of the case.

The Obama administration recently waded into a similar lawsuit in New York on the same grounds.

By using such court filings in civil rights cases, the Obama administration is saying it has an interest in preserving constitutional rights in the same way it has an interest in foreign policy. There are examples of past administrations using statements of interest to coax public policy — such as in 2005 when the Bush administration intervened in the case over whether to keep Terri Schiavo, a Florida woman with severe brain damage, on life support. But neither career Justice Department officials nor longtime advocates can recall such a concerted effort to insert the federal government into local civil rights cases.