Colleen McCullough represents clients in patent, trademark and other complex litigation matters in federal court. Ms. McCullough has managed all stages of litigation, from the initial pleadings through trial. She has handled discovery in multi-party and multi-district litigations, argued discovery and claim construction motions in federal court, taken and defended depositions of both fact and expert witnesses, prepared petitions for inter partes review and advised clients on important strategic matters.

At trial, Ms. McCullough has taken the testimony of and cross-examined fact and expert witnesses. For client Bombardier Recreational Products, Ms. McCullough presented two witnesses in a federal trial in which the jury returned a full defense verdict rejecting a $130 million trademark infringement claim. Ms. McCullough also presented and cross-examined expert witnesses in a jury trial defending against patent infringement claims for client GE. In a case brought with the ACLU against New England’s US Immigration and Customs Enforcement office, she cross-examined the New England Field Office Director in a hearing that led to the release of the firm’s clients from unlawful immigration detention. 

Ms. McCullough has also authored briefs in appeals before the Massachusetts Supreme Judicial Court, the US Courts of Appeals for the Ninth and Federal Circuits and the US Supreme Court.

Ms. McCullough has represented clients in patent cases in a range of technological fields, including pharmaceuticals, biotechnology, software and mechanical engineering. She was named a One to Watch by Best Lawyers in America in 2024.

Before joining WilmerHale, Ms. McCullough was a law clerk to the Honorable Thomas N. O'Neill of the United States District Court for the Eastern District of Pennsylvania. Previously, Ms. McCullough served as primary draftsperson for the University of Pennsylvania's Criminal Law Research Group, where she assisted the international effort to redraft Somalia's criminal code. Ms. McCullough earned her JD from the University of Pennsylvania Law School, where she was an Articles Editor for the University of Pennsylvania Law Review. 

Ms. McCullough is admitted to practice in the Commonwealth of Massachusetts and before the United States District Court for the District of Massachusetts, the Eastern District of Michigan, and the United States Courts of Appeals for the Ninth Circuit and the Federal Circuit.