There are a variety of federal government agencies doing a range of legal work. There are many resources online that you can use to try to determine which agency you would like to work for. Check out these links below to start learning what it would be like to work at a federal agency, and how to become most competitive for that position.
Leadership Directory (Federal Yellow Book)
Department of Justice
The Department of Justice is the biggest legal employer in the world! Many DOJ attorneys get their start through the DOJ Honors Program, while others are directly hired after cultivating experience litigating or in a specific area of law.