WASHINGTON  Judge Sonia Sotomayor’s judicial opinions are marked by diligence, depth and unflashy competence. If they are not always a pleasure to read, they are usually models of modern judicial craftsmanship, which prizes careful attention to the facts in the record and a methodical application of layers of legal principles.

Judge Sotomayor, whom President Obama announced Tuesday as his choice for the Supreme Court, has issued no major decisions concerning abortion, the death penalty, gay rights or national security. In cases involving criminal defendants, employment discrimination and free speech, her rulings are more liberal than not.

But they reveal no larger vision, seldom appeal to history and consistently avoid quotable language. Judge Sotomayor’s decisions are, instead, almost always technical, incremental and exhaustive, considering all of the relevant precedents and supporting even completely uncontroversial propositions with elaborate footnotes.

All of which makes her remarkably cursory treatment last year of an employment discrimination case brought by firefighters in New Haven so baffling. The unsigned decision by Judge Sotomayor and two other judges, which affirmed the dismissal of the claims from 18 white firefighters, one of them Hispanic, contained a single paragraph of reasoning.