James Ostrowski obtained a degree in philosophy from the State University of New York at Buffalo in 1980 and graduated from Brooklyn Law School in 1983. In law school, he was writing assistant to then Dean David G. Trager, now a federal judge in the Eastern District of New York. He was also a research assistant to Associate Dean Henry Mark Holzer (now professor emeritus). He was a member of the Moot Court Honor Society and an award-winning member of the International Law Moot Court Team. One of his assignments for Dean Trager was to draft a report for the Association of the Bar of City of New York in support of the individual assignment system for state courts (each case would stay with one judge till the end). That system was soon adopted throughout New York State and remains in effect today.

After graduation, he joined the Special Litigation Unit at the Manhattan firm, Bower & Gardner, at that time the leading insurance defense firm in the state. He was admitted to the New York Bar in January, 1984, and the New Jersey Bar in 1985 (resigning in good standing in 1995). His desire for professional independence led him to open his own law office in 1985, practicing in New York City, New Jersey, and his hometown of Buffalo. He moved his office to Buffalo in 1988.

He served as vice-chairman of the law reform committee of the New York County Lawyers Association (1986-88) and wrote two widely quoted reports critical of the law enforcement approach to the drug problem. He is currently chair of the human rights commitee, Erie County Bar Association. He has written a number of scholarly articles on the law on subjects ranging from drug policy to the commerce clause of the constitution. His op-ed articles have appeared in the Wall Street Journal, Buffalo News, Cleveland Plain Dealer and Legislative Gazette. His policy studies have been published by the Hoover Institution at Stanford University, the Ludwig von Mises Institute at Auburn University, and the Cato Institute in Washington, D.C.

He has lectured and debated widely on issues related to the law and appeared on a number of national television and radio programs. He has been a guest lecturer at the S.U.N.Y. Buffalo Medical School since 1991 and is an adjunct scholar at the Ludwig von Mises Institute at Auburn University.