What law made agreements such as "restrictive covenant" illegal

Racially exclusive restrictive covenants, which were widely used in the United States during the first half of the 20th century, were declared unenforceable in 1948 by the Supreme Court under the equal protection clause of the Constitution's 14th Amendment.

“destroyers for bases agreement in the destroyers for bases agreement between the united states and the united kingdom on september 2, 1940, fifty caldwell , wickes, and clemson class us navy destroyers were transferred to the toyalbnavy from the united states navy in exchange for land rights on british possessions.” i hope this you .