14th amendment is the one used by the Supreme Court to overturn court decisions in order to enforce equal rights.
The 14th amendment states that all citizens born or naturalized in the US are US citizens. Along with this, the amendment states that these individuals must receive equal protection under the law. This means that they must have all the rights/liberties guaranteed to them in the US Constitution.
This amendment has been used several times in the Supreme Court. An example of this would be the case Brown vs. Board of Education. This 1954 Supreme Court case ruled that public segregated facilities, like schools, violated the Equal protection clause of the 14th amendment.