The original Act was first passed in 1950 by the National Conference of Commissioners on Uniform State Laws. It was amended in 1952 and again in 1958. The most recent amendments were enacted in 1968 and included improved machinery for finding the person owing support; guidelines for the conduct of the trial in the responding state; guidelines for cases where paternity is in question or where there has been interference with visitation rights; and simplified procedures for registering and enforcing out-of-state support orders. Such acts, substantially similar in content, have been passed in all 50 states.