Ackerberg v. Johnson Court held that seller of unregistered securities was entitled to Rule 144 exemption, because he was neither an "issuer", "underwriter" or "dealer".
SEC v. Cavanagh Court upheld district court's judgment that defendants violated Section 5 of the Securities Act of 1933 by selling and offering to sell unregistered securities, not exempted under Rule 144.
SEC v. Lybrand Court held in favor of the SEC. "In sum, dendants' transactions fall squarely within the ambit of Section 5 and are not entitled to exemption pursuant to Section 4(1) or Rule 144."
SEC v. Ralston Purina Co. In this seminal Supreme Court opinion, the Court established the precedent for complying with the Securities Act of 1933 reguiring the registration of securities and full disclosure to the public regarding private placement of securities.