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.

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.

As an initial matter, the Supreme Court clarified the requirements of proving a claim of anti-competitive behavior under Section 1 of the Sherman Act.

In Twombly, the court adopted a stricter "plausibility" standard that required "enough fact[s] to raise a reasonable expectation that discovery will reveal evidence of illegal agreement."

In keeping with these principles a court considering a motion to dismiss can choose to begin by identifying pleadings that, because they are no more than conclusions, are not entitled to the assumption of truth.

[3] On July 22, 2009, after the Supreme Court broadened Twombly with its decision in Iqbal, Senator Arlen Specter introduced the Notice Pleading Restoration Act of 2009, which provided:[7] Except as otherwise expressly provided by an Act of Congress or by an amendment to the Federal Rules of Civil Procedure which takes effect after the date of enactment of this Act, a Federal court shall not dismiss a complaint under rule 12(b)(6) or (e) of the Federal Rules of Civil Procedure, except under the standards set forth by the Supreme Court of the United States in Conley v. Gibson, 355 U.S. 41 (1957).4 Shortly thereafter, a similar bill was introduced in the US House of Representatives.