First Amendment
Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
The government is not to make any law prohibiting the exercise of free speech. The law in question would be the same as saying whenever someone wants to say something of a political nature inside your private place of business you have to let them inside to give their $0.02.