It's a right because it has been legislated as being so. Legislation can be changed so that it is no longer permitted.
Jackaroe, I don't think that that could be constitutional, because it would interfere with our right to freedom of association.
Since Kulindahr has more knowledge on this matter than I do, I'm going to pass the ball to him. (here, Kulindahr, catch!)
Thanks so much.
Let's start with the Declaration of Independence: rights are endowed, bestowed, inalienable. As Jefferson explained, rights belong to the people, who assign some to the government, giving it authority.
Government cannot, therefore, grant rights. It can only give what already belongs to the citizens. If it can grant joint bargaining, it does so only because that is already a right of the people.
Forming a union is nothing but an exercise of the right of freedom of association. Collective bargaining is nothing but freedom of choice, freedom of action, growing out of that freedom of association.
Individuals own themselves. All interaction between individuals is thus between two sovereign entities. Since each is equally sovereign, interaction is thus between equals. When equals interact, and there is agreement, the agreement is contractual, because it is based on the agreement of equals.
A union is thus a contractual organization which rests on the individual self-ownership of the members. Since the members have agreed that none will work for more, nor for less, than any of the others, that is part of the contract.
When individuals contract together to form a corporation, we treat that corporation as a single entity, a contractual entity. A union is the same: they are a single entity.
Since both entities have come about by free contractual association of self-owning individuals, they are equal entities. This is so whether the union, or the corporation, consists of a thousand, a hundred, or just one. And if the corporation wants to negotiate with just one of the individuals in the union, it must negotiate with all -- because that is their contract.
If government wants to say individuals may not do so, they are stealing the exercise of rights.