Secret memos obtained by The New York Times illuminate the origins of the court’s now-routine “shadow docket” rulings on presidential power.

Just after 6 p.m. on a February evening in 2016, the Supreme Court issued a cryptic, one paragraph ruling that sent both climate policy and the court itself spinning in new directions.

For two centuries, the court had generally handled major cases at a stately pace that encouraged care and deliberation, relying on written briefs, oral arguments and in-person discussions. The justices composed detailed opinions that explained their thinking to the public and rendered judgment only after other courts had weighed in.

But this time, the justices were sprinting to block a major presidential initiative. By a 5-to-4 vote along partisan lines, the order halted President Barack Obama’s Clean Power Plan, his signature environmental policy. They acted before any other court had addressed the plan’s lawfulness. The decision consisted of only legal boilerplate, without a word of reasoning.