Louis Fisher is a leading national expert on the separation of powers. The author of 16 books often has his work cited in Supreme Court briefs, and he even merited a mention as an authority on war powers during Justice Samuel Alito Jr.’s confirmation hearings. But at age 71, instead of resting on his laurels or winning accolades for his work, the soft-spoken scholar appears to be on the verge of getting fired for being too opinionated.

Fisher is a senior specialist at the Congressional Research Service, a branch of the Library of Congress that has a long tradition of analyzing policy issues and drawing conclusions — in Fisher’s case, often in favor of congressional over executive power.