In the case of Transamerica Mortgage Advisors, Inc. (TAMA) v. Lewis in 1979, the U.S Supreme Court ruled that there is no implied private right of action for damages under Section 206 of the Investment Advisers Act of 1940. The plaintiff, Lewis had sued TAMA and its president alleging they violated their fiduciary duties by selling properties at prices significantly below market value to companies they controlled or were affiliated with without disclosing these actions to him as a client. However, the court held that while Section 206 prohibits certain conduct and provides criminal penalties for violations, it does not explicitly provide or imply a right for private individuals to sue for damages resulting from such violations.

In the dissenting opinion for Transamerica Mortgage Advisors, Inc. (TAMA) v. Lewis, Justice William Rehnquist argued that the majority's interpretation of Section 206 of the Investment Advisers Act was incorrect and overly broad. He contended that this section does not provide a private cause of action for damages to clients who have been defrauded by their investment advisers. According to him, if Congress had intended such an expansive remedy, it would have explicitly stated so in the statute as it did in other sections where private rights were granted expressly. Furthermore, he pointed out that there are already existing remedies under state law and common law principles which can protect investors from fraudulent practices by their advisers without needing to stretch federal statutes beyond what is written.