 Sotomayor cast her first vote as an associate Supreme Court justice on August 17 , 2009 , in a stay of execution case . She was given a warm welcome onto the Court and was formally invested in a September 8 ceremony . Sotomayor 's inaugural case in which she heard arguments was on September 9 during a special session , Citizens United v. Federal Election Commission . It involved the controversial aspect of the First Amendment and the rights of corporations in campaign finance ; Sotomayor dissented . In her vigorous examination of Floyd Abrams , representing the First Amendment issues in the case , Sotomayor challenged him , questioning 19th century rulings of the Court and saying , " What you are suggesting is that the courts , who created corporations as persons , gave birth to corporations as persons , and there could be an argument made that that was the Court 's error to start with ... [ imbuing ] a creature of State law with human characteristics . " 
