In a sign of just how far a recent Supreme Court decision on age discrimination could reach into labor law, a federal judge on Friday cited the opinion as she ruled against a woman who had sued Washington, D.C., under the city’s juror protection law.

LilliAnn Williams-Jackson, a former guidance counselor at J.O. Wilson Elementary School, filed suit against the city in 2007, alleging she was transferred out of her job at the school because her principal was angry that Williams-Jackson had spent four months serving on a jury.