In the US, there is no constitutional right to collective bargaining
For something to be unconstitutional, it needs to be protected by the Constitution. Generally, things protected by the Constitution are known as constitutional rights. These constitutional rights are protected against laws that would remove them. Collective bargaining is not a right guaranteed by the Constitution, and the belief that the rights to assemble and petition the government (and also the inferred right of association) means that collective bargaining is a protected right is an incorrect understanding of what collective bargaining is.
Collective bargaining is governed primarily by the National Labor Relations Act, which is for private employers, not the government. Government employee collective bargaining is allowed only via separate federal and state laws. Some states may have this as a right in their Constitution, but Texas is not one of them. Others may not allow public sector employees full labor "rights." Florida's Constitution, for example, explicitly prohibits public sector employees from striking.
The NLRA is a law, not a right. Collective bargaining is not association, it is the act of negotiating work conditions and pay. it is not the same as union membership.
There seems to be confusion on what collective bargaining is, versus what membership in a union is. Anyone with appropriate employment can join a union. You are free to associate with whomever you want, including paying a union to be a member. This is not the same as allowing that union to perform collective bargaining with the employer, which can just ignore a non-recognized union.
The NLRA states that employers must recognize and deal with unions if the union is properly selected by the employees. It's a law, not a right. If the NLRA were repealed tomorrow, unions in the US would find themselves severely limited in their power, and they would find no protections in the Constitution.
In the absence of the NLRA employers would be free to completely ignore any union, and not have meetings, discussions, or anything else. Only the NLRA prevents firing employees due to union activity, so without the NLRA, employers could just fire anyone found to be supporting union membership. Being pre-union is not a protected class. Most states allow employers to fire people for almost anything, so firing people for membership in a union would likely be easy for private employers. It's a false equivalency, but few would have a problem with a business firing people who were members of the Klan. I suppose the right to assemble would prevent governments from firing employees for membership alone. Certainly employees can get together and try to influence employers, but history shows that without laws behind them, these efforts generally fall short.
For public employees, the ability to organize for collective bargaining is strictly created by laws that allow and require governments to recognize the unions. Without these laws, employees can feel free to join a union, but they will quickly find that not having a law behind them to force the government to recognize the union makes the effort to change the workplace much much harder. My opinion is that such unions primarily exist to get press and have very little affect on the workplace. This would be similar to private sector unions that have not been voted in and thus are not recognized by management (like the Alphabet Workers Union, which seems to mostly issue press releases). Further, there is nothing prohibiting the outlawing of public sector workers from striking, which means that the union will be quite ineffective.
I am aware of no successful legal challenges to prohibitions on public sector collective bargaining. This is a political issue, not a legal one.
The National Labor Relations Act does not apply to government employers:
The term "employer" includes any person acting as an agent of an employer, directly or indirectly, but shall not include the United States or any wholly owned Government corporation, or any Federal Reserve Bank, or any State or political subdivision thereof, or any person subject to the Railway Labor Act [45 U.S.C. § 151 et seq.], as amended from time to time, or any labor organization (other than when acting as an employer), or anyone acting in the capacity of officer or agent of such labor organization.
My final edit is this:
Those who believe that collective bargaining by government empoyees is a protected right are invited to go to Georgia and overturn the law there, which prevents this activity except by firefighters and police.
