The cost of litigating a U.S. Supreme Court case from filing to decision can be upward of $1 million when a private law firm is involved. But sometimes a party gets lucky, like the city of Philadelphia recently, and hires some of the best advocates in the bar for little or nothing.

Hogan Lovells partner Neal Katyal, a former acting U.S. solicitor general who has argued 44 cases before the justices, handled the merits briefing and arguments pro bono in a contract with Philadelphia in last term’s high-profile clash between a foster care agency’s religious rights and the city’s anti-discrimination policy—Fulton v. City of Philadelphia.