Her confirmation assured, Elena Kagan is on the brink of becoming the fourth woman ever to serve as a Supreme Court justice. The Senate is set Thursday to confirm President Barack Obama's nominee, whose addition to the court will mark the first time three female justices have served concurrently. Nearly all Democrats, the Senate's two independents and a handful of Republicans are backing her. The vote is to be one of the Senate's last actions before its members depart for a monthlong vacation. Republicans have harshly criticized Kagan, 50, as a political activist who would be unable to put...