Bell Atlantic Corp. v. Twombly, 550 U.S. 544 (2007), was a decision of the Supreme Court of the United States involving antitrust law and civil procedure. Authored by Justice David Souter, it established that parallel conduct, absent evidence of agreement, is insufficient to sustain an antitrust action under Section 1 of the Sherman Act. It also heightened the pleading requirement for federal civil cases by requiring for plaintiffs to include enough facts in their complaint to make it plausible, not merely possible or conceivable, that they will be able to prove facts to support their claims. The latter change in the law has been met with a great deal of controversy in legal circles, as evidenced by the dissenting opinion from Justice John Paul Stevens.