From 2007 to 2009, Eisen was active in the presidential campaign of his law school classmate Barack Obama before joining the transition team of then-President-elect Obama as deputy counsel.
On January 20, 2009, Obama named him Special Counsel for Ethics and Government Reform in the White House.
Eisen joined the Brookings Institution as a Visiting Fellow in September 2014. He is now a Senior Fellow in their Governance Studies program. At Brookings he has contributed to reports on open government, the emoluments clause, presidential obstruction of justice, and anti-corruption efforts in the natural resource sector. A prolific writer, he often contributes [lefty] op-ed pieces to The New York Times, The Washington Post, Politico, USA Today, and other national publications.