Even legal giants face setbacks, and for Gibson, Dunn & Crutcher partner Theodore Olson, who successfully argued the seismic sports-betting case before the U.S. Supreme Court this term, that meant first having to overcome “six or seven” losses in the lower courts.

So when the justices on Monday sided with him 6-3 (or 7-2, depending on how you tally it) and struck down a 1992 federal law prohibiting most states from licensing sports betting, it was a sweet win—and one with monster, market-moving implications.