WASHINGTON — A partner in the Washington office of the law firm DLA Piper lobbied without pay this year to find a way through legislation to increase corporate gifts of food to America’s hungry.

After hours of persuasion on Capitol Hill, Evan Migdail was instrumental in adding to the Pension Protection Act of 2006 a provision that gave businesses a larger-than-usual charitable deduction for donations of food to tax-exempt organizations. The new law is expected to generate more than $250 million a year in additional gifts of food to America’s Second Harvest: The Nation’s Food Bank Network.

Law firms and lobbying companies all over Washington offer their services free to deserving groups and causes. But many readers would be surprised that lobbyists do good at all. In fact, the first part of the new Congress next year will be largely devoted to enacting ways for lawmakers to distance themselves from professional favor-seekers.

Many question whether lobbying, pro bono or not, can ever be praiseworthy. After all, lobbyists work to get taxpayer-funded goodies for their clients and thus reduce the amount that the public at large can keep for itself.

A vice president of the Cato Institute, David Boaz, said, “Some of us don’t think every good impulse deserves a forced transfer from the taxpayers.”

Nonetheless, lobbyists do have hearts and they prove it regularly.

A lawyer for WilmerHale, Edward Tobin, and his team, helped persuade federal authorities to drop deportation proceedings against a Senegalese immigrant, Amadou Ly, who overstayed his visa when his mother abandoned him in America at age 14. Mr. Ly’s illegal status was discovered because he was a gifted student; he helped his East Harlem high school robotics team reach a national competition, but he couldn’t travel to the contest because he did not have the proper documents.

Thanks to the work of Mr. Tobin and his colleagues, White House officials, a bipartisan group of federal lawmakers, and Mayor Bloomberg, the Senegalese ambassador, Amadou Lamine Ba, intervened, and Mr. Ly was able to remain in America to continue his education.

Along similar lines, the law firm Holland & Knight helped engineer the release of Cuc Foshee from custody in Vietnam. Led by Mr. Foshee’s daughter, lawyers from Holland & Knight drummed up publicity about the situation and persuaded Senator Martinez, a Republican of Florida, to block a trade bill with Vietnam until Mr. Foshee was released.

Charity is not always a matter of life and death. Patton Boggs, the lobbying law firm, organized a visit on Capitol Hill last spring for Operation Smile, a nonprofit organization that provides reconstructive surgery for children in developing countries who have facial deformities.

DLA Piper partner John Merrigan and others organized conferences in Washington that drew Senator Clinton, Senator Snowe, a Republican of Maine, and entertainers Lil’ Kim and Chaka Khan to focus policy-makers on the need for more funding for foster children. The firm also worked on mentoring provisions in the reauthorization of the No Child Left Behind Act and on appropriations for a model mentoring program in Los Angeles.

An African-American-owned law and lobbying firm, Andrews & Bowe, pressed for legislation that benefits working families, seniors, and small business owners who have fallen victim to predatory lending and abusive debt collection practices.

Habitat for Humanity, which builds homes for the poor around the country, has benefited from free lobbying advice for years.

Partners at the Smith-Free Group, Timothy Locke, a Republican, and James Free, a Democrat, have worked for different presidents — Mr. Locke for President Reagan and Mr. Free for President Carter. Now they are both working on behalf of the same president: James Knox Polk, who, like both lobbyists, is a native of Maury County, Tenn. Messrs. Locke and Free are seeking funding for the James K. Polk Memorial Association in Columbia, Tenn., to honor the nation’s 11th president. That pro bono task begins in earnest next week with the start of the 110th Congress.