Jim represents clients in the areas of defense, government contracting, trade, foreign relations, economic development, renewable energy, technology, health, education, and finance among others. Jim represented the Northern Virginia communities of Arlington, Alexandria, and Fairfax County for 24 years in the United States Congress, where he  was known for his bipartisan leadership and ability to resolve complex issues. He served on the Appropriations, Foreign Affairs, Banking, Housing and Finance, and Government Reform and Oversight committees during his 12 terms in the U.S. Congress. As a senior member of the House Appropriations Committee, he was chairman and ranking member of the Subcommittee on the Interior and Environment, a senior member on the Defense and Military Construction subcommittees: Foreign Operations, Labor, Health, and Human Services, and Ranking Member of the D.C. and Legislative Branch subcommittees.

Jim was a founder of the New Democrat Coalition (NDC), which is now the largest caucus in the U.S.   congress. The NDC is defined by its advocacy for international trade, support for small business, fiscal responsibility, and entrepreneurial innovation, especially in the tech industry. He also served as a member of the Steering and Policy Committee of the House Democratic Leadership.

Jim oversaw the budgets for the Environmental Protection Agency, Indian Affairs, Forest Service, the Bureau of Land Management, the Smithsonian, and the National Endowment for the Arts and the Humanities. As a senior member of the Defense Appropriations Subcommittee for 20 years, he oversaw all aspects of the defense budget, including weapons procurement, cybersecurity, research and development, military medical research, military base closures, civilian personnel, and overseas contingency operations.

Among major projects in Northern Virginia, Jim helped obtain $1.5 billion for extending Metrorail to Dulles International Airport; $2.5 billion to replace the Woodrow Wilson Bridge between Washington, D.C. and Alexandria, Virginia; $180 million to widen Route 1 in Fairfax County, and hundreds of millions of dollars in support of Virginia schools, housing, health centers, and infrastructure. He directed billions of dollars into government contracting in his district and added 20,000 military personnel to his Congressional district in the last round of military defense (BRAC) closures.

Prior to joining Congress, Jim served as Mayor of the City of Alexandria, Va. (1985–1990); Senior Specialist, Budgetary, Fiscal Policy for the Library of Congress (1972–1974); and Acting Director of the Budget Office for Welfare, Medicare, Medicaid, and Social Services for the U.S. Department of Health and Human Services (then HEW) (1968–1972).

Community
Board Member, George Mason University Board of Visitors (2026-present)
Board Member, Association of Former Members of Congress (2015–present)
Board Member, Middle East Policy Council (2021-present)
Board Member, Diplomacy Center Foundation (2022-present)
Board Member, Government Blockchain Association (2015–present)
Advisory Board Member, Virginia Tech Graduate School of Public and International Affairs (2016-present)
Advisory Board Member, RegulatingAI (2024-present)
Chairman, Fort Monroe Authority (2016–2024)
Chairman, World Affairs Council (2018–2019)
Board Member, Sister Cities International (2015–2018)
Board Member, Open World Institute of the Library of Congress (2013–2015)