The Affiliated Ute Citizens of Utah v. United States case in 1971 revolved around the sale of shares owned by mixed-blood members of the Ute Indian Tribe to non-Indians, which was facilitated by two bank employees. The plaintiffs argued that they were deceived into selling their shares at prices significantly below market value due to fraudulent misrepresentations and omissions made by these individuals. The Supreme Court ruled in favor of the plaintiffs, stating that under Section 10(b) of the Securities Exchange Act and Rule 10b-5 implemented by the SEC, it is unlawful for any person to engage in fraud or deceit upon any other person in connection with securities transactions. This includes not only making false statements but also omitting material facts necessary to make statements not misleading. Therefore, even if no positive proof of reliance on these deceptions could be shown (as defendants claimed), a presumption thereof existed given defendants' roles as insiders privy to undisclosed information.

In the dissenting opinion for Affiliated Ute Citizens of Utah v. United States, Justice Harlan argued that the majority's decision was based on a misinterpretation of Section 10(b) and Rule 10b-5 under the Securities Exchange Act. He contended that these provisions were not intended to cover all fraudulent schemes in connection with securities transactions but only those involving manipulative or deceptive devices employed in buying or selling securities. The justice further stated that there was no evidence showing any manipulation or deception by defendants during their purchase of shares from plaintiffs, thus they should not be held liable under Section 10(b). Additionally, he criticized the majority’s reliance on presumptions rather than actual proof to establish liability and damages against defendants.