What is public law?
public law meaning A bill or joint resolution (other than for amendments to the Constitution) passed by both Houses of Congress and approved by the President. Bills and joint resolutions vetoed by the President, but then overridden by the Congress also become Public Law. Public Laws affect society as a whole, and most laws passed by Congress are Public Laws. Public Law citations include the abbreviation, Pub.L., the Congress number (e.g. 107), and the number of the law. For example: Pub.L. 107-006.
reference: Ben’s Guide U.S. Government – Glossary