If the Popes are infallible, the laws of earlier Popes must be those of later Popes—yet the laws of the Catholic Church have varied.

The Catholic Answers

It is not necessary that all the laws of earlier Popes must be those of later Popes. Infallibility concerns doctrine, and morals, not necessarily discipline. Disciplinary laws adapted to particular times change with the times.

Radio Replies Volume 1 by Rev. Dr. Leslie Rumble MSC and Rev. Charles Mortimer Carty