Alito, painted by opposition Democrats as an ultra conservative during his confirmation proceedings, sided with the majority in upholding a stay of execution for a convicted murderer late Wednesday.
The state of Missouri appealed a prior ruling from a lower court that delayed the execution of Michael Anthony Taylor. But the Supreme Court in a 6-3 ruling supported Taylor's right to another hearing.
The court's other conservatives all voted to allow the execution to go forward.
It has been a whirlwind week for Alito, who was confirmed and sworn in Tuesday, then participated in President George W. Bush's State of the Union address and cast his first vote on the Supreme Court not long after a ceremonial swearing in ceremony Wednesday.
