The excerpt above is part of the 14th amendment. This amendment was passed in 1868 and was supposed to help protect newly freed slaves. The goal in passing this was to ensure that African-Americans had the same legal rights as white citizens.
This due process clause has been used in several important Supreme Court cases to protect American citizens.
Whenever any form of government becomes destructive of these ends, it is the right of the people to alter or to abolish it, and to institute new government
President Johnson accused the North Vietnamese of attacking a US Naval Vessel in the Gulf of Tonkin.
History has shown this to have probably been fabricated.