The first of May has been National Law Day since a joint resolution of Congress in 1961 so designated the date. Eisenhower was the first president to proclaim a National Law Day, and every president since has issued his own proclamation. You can read their proclamations at the Law Day Presidential Proclamations Archive.
Why is there a National Law Day? There are so many "declared" holidays we barely acknowledge as they pass by. For example, did you know that May 11 is Eat What You Want Day? How about Cellophane Tape Day on May 27? Although cellophane tape is quite significant (even in the legal field), it's more beneficial to take a moment to think about the importance of the law. The holiday is meant to give Americans a chance to reflect on the ideals of equality and justice that our legal system protects, as well as to cultivate a respect for the law. It may come as no surprise that there is a law establishing National Law Day, under Title 36 of the U.S. Code.
Today, be sure to wish someone you know a Happy Law Day!