Professor Andonian is a member and co-founder of Caleb Andonian PLLC, a boutique litigation firm in Washington, D.C.  His practice is focused on representing individuals who have been charged with a crime, are being investigated by the government, have been subjected to unlawful working conditions, or have been seriously injured by someone else's misconduct.  A formidable and highly respected litigator, Professor Andonian has tried more than two dozen cases to verdict and has helped many clients through the complexities of civil discovery and motions practice.  He also regularly represents clients in administrative hearings and arbitrations.

Prior to co-founding Caleb Andonian, Professor Andonian was Of Counsel at one of the country's leading labor and employment firms, located in D.C., where he represented local and international unions in all manners of litigation at the local, state, and federal levels.  Prior to that, he was an attorney in the trial and appellate divisions of the public defender's office in D.C. - widely regarded as one of the best trial offices in the country - and before that he served as a law clerk to the Honorable Robert E. Morin, a former Chief Judge of the D.C. Superior Court.  Before moving to D.C. Professor Andonian spent time as an associate at a boutique criminal-defense firm in northern California.

In addition to teaching at AUWCL, Professor Andonian serves as a faculty member of Harvard Law School's Trial Advocacy Workshop.  He also frequently leads litigation training for experienced lawyers around the country.

Professor Andonian is a member of the Edward Bennet Williams American Inn of Court, an invitation-only professional organization that has the distinction of being one of only a few Inns of Court focusing on white-collar criminal prosecution and defense, and includes judges from the D.C. Circuit, D.C. District Court, and D.C. Superior Court, as well as officials from the U.S. Department of Justice and some of the most established defense attorneys in Washington, D.C.

In July 2021, Professor Andonian was elected to a three-year term as a member of the D.C. Bar's Litigation Steering Committee.  He also serves by appointment as an alternate hearing committee member for the D.C. Board on Professional Responsibility.