The right to unionize your workplace isn't just protected by the National Labor Relations Act -- it's protected by the U.S. Constitution.
The First Amendment of the Constitution, which guarantees the freedom of speech, assembly, and petition, also guarantees freedom of association and is recognized by U.S. courts as a fundamental right. The freedom of association encompasses the right of the group to take collective action to pursue the interests of its members. For this obvious reason, the constitutionally protected freedom of association includes unionization and union-related activities.
Additionally, the freedom of association for the advancement of shared values is inseparable from "liberty" assured by the Due Process Clause of the Fourteenth Amendment.
When politicians make it harder to join a union and employers use union-busting tactics, they're not just violating federal law, they're infringing on our constitutional right to unionize. Period.
Read more about the right to unionize here.