In more recent decades, legislation has been passed that emphasizes the identification and protection of cultural sites, especially those on public lands. In the United States, the most notable of these laws remains the National Historic Preservation Act. The administration of President Lyndon B. Johnson was most instrumental in passing and developing this legislation, although it has been extended and elaborated upon since. These laws make it a crime to develop any federal lands without conducting a cultural resources survey in order to identify and assess any cultural sites that may be affected. In the United Kingdom, PPG 16 has been instrumental in improving the management of historic sites in the face of development.