SAN FRANCISCO — It’s many a lawyer’s worst nightmare—when one missed deadline washes an entire case down the drain.

That’s what happened this week to a team of Washington, D.C. lawyers with Paul, Weiss, Rifkind, Wharton & Garrison. They’ve spent more than a year litigating individual price fixing claims on behalf of client Sharp Electronics Corp., only to inadvertently miss the deadline to opt out of a class settlement in the case.