US Code, Title 36, Section 164

The first day of May of each year is hereby designated as Law Day, U.S.A. It is set aside as a special day of celebration by the American people in appreciation of their liberties and the reaffirmation of their loyalty to the United States of America; of their rededication to the ideals of equality and justice under law in their relations with each other as well as with other nations; and for the cultivation of that respect for law that is so vital to the democratic way of life.

The President of the United States is authorized and requested to issue a proclamation calling upon all public officials to display the flag of the United States on all government buildings on such day and inviting the people of the United States to observe such day with suitable ceremonies and other appropriate ways, through public bodies and private organizations as well as in schools and other suitable places.