Regulation S

Regulation S is a "safe harbour" that defines when an offering of securities will be deemed to come to rest abroad and therefore not subject to the registration obligations imposed under Section 5 of the 1933 Act. The regulation includes two safe harbour provisions: an issuer safe harbour and a resale safe harbour.
Section 5 of the 1933 Act is meant primarily as protection for United States investors. As such, the U.S. Securities and Exchange Commission had only previously, weakly enforced registration of foreign transactions, and only had limited constitutional authority to do so.