The National Labor Relations Board (NLRB) has just overruled a previous case that had expanded the definition of independent contractor for the purposes of the National Labor Relations Act. In its SuperShuttle DFW Inc. decision, the board has brought that definition into greater alignment with the definition used by other agencies such as the Department of Labor and the IRS.
When we think about speech protections, we often think of the First Amendment to the U.S. Constitution. The First Amendment only prohibits governmental actors from abridging freedom of speech, so it doesn't apply to private actors such as non-government employers. (The First Amendment does apply to government employers.)