Clement resigned on May 14, 2008, effective June 2, 2008, and joined the Georgetown University Law Center as a visiting professor and senior fellow at the Supreme Court Institute.

While at Georgetown, Clement successfully competed in the American Parliamentary Debate Association as part of the university's Philodemic Society.

[8] He was also one of eight editors of the law review's annual lampoon who oversaw publication of a satirical piece mocking an article by Mary Joe Frug on the one-year anniversary of her murder.

After his clerkships, Clement entered private practice as an associate in the Washington, D.C. office of the law firm Kirkland & Ellis.

[11] On August 27, 2007, President Bush named Clement as the future acting Attorney General of the United States, to take office upon the resignation of Alberto Gonzales, effective September 17, 2007.

[14][15] Clement gave notice of his resignation on May 14, 2008, effective June 2, 2008, and returned to Georgetown University Law Center as a senior fellow.

"[18] Clement joined Bancroft PLLC, a boutique law firm led by former Assistant Attorney General Viet D.

[19][20] Clement led the challenge on behalf of 26 states to overturn the Patient Protection and Affordable Care Act in the Supreme Court on March 26–28, 2012.

The Court upheld the "individual mandate" as a tax, but found the States could not be compelled to follow the portion of the law relating to Medicaid expansion.

[22] In 2019, Clement was an attorney for the appellants in the landmark Rucho v. Common Cause Supreme Court case, in which partisan gerrymandering was declared a non-justiciable issue.

In June 2022, following his clients' Supreme Court victory in New York State Rifle & Pistol Association, Inc. v. Bruen, Clement separated from Kirkland & Ellis, after the firm announced it would "no longer handle Second Amendment litigation.