I believe I am not far off the mark in suggesting that the civil tort of conspiracy (as opposed to the charge of conspiracy under criminal law) came into its own in the modern era in the formative years of the labor movement. A strike, to put it simply, is an attempt by the workers to put pressure on the company by making it difficult for the company to carry on its business. The beauty of the strike as a weapon is that every individual worker is free to choose whether or not he wishes to work on any given day. The only recourse the company has against a worker who chooses not to show up (beyond simply not paying his wages) is to refuse to allow that worker to return to his job should he eventually change his mind. If the worker does not possess some exceptional skill that is very difficult to replace, the threat or act of refusing to work is not an effective bargaining tool.
Unless, of course, all the workers decide to exercise that choice at the same time. Then the employer has a problem. He can try to hire replacement workers, but that can be difficult and time consuming. One option explored by employers in the early days of the union movement was to bring civil action against the workers for conspiracy. The claim was that the decision to not work, while not actionable if exercised by individual workers, became actionable if it was done en masse as part of an organized attempt to damage the company.
Is it really fair that you can be held accountable for actions that are perfectly legal, simply because you are acting in concert with a number of other people who are also behaving legally? That's what the law of conspiracy says. It may seem wrong, but the fact is that the group can exercise power far beyond what individuals acting on their own can do. The law simply recognizes that here and there are instances where the abuse of that power becomes so unfair as to demand legal remedy.
And so it was that initially, judges would find in favor of the company and awarded damages against the union. But that situation did not last long. With the passage of time, the courts found that the use of conspiracy laws against the workers was even more unfair than the alternative; and they formulated a new legal doctrine: that what is legal for the individual does not automatically become illegal when done en masse, unless it could be shown that the purpose of the action was specifically to cause damage to the struck party. The unions argued that their primary motivation was not to hurt the company, but to better the lot of the workers, and this argument was accepted by the courts. It essentially stands to this day as the guiding principle of the Tort of Conspiracy.
But that does not provide an excuse if the primary purpose of the conspiracy was not to promote its own legitimate interests, but to damage the interests of the other party. In Cement Lafarge v BC Lightweight Aggregate (1983), Justice Estey of the Supreme Court of Canada summarized the law as follows:
Although the law concerning the scope of the tort of conspiracy is far from clear, I am of the opinion that whereas the law of tort does not permit an action against an individual defendant who has caused injury to the plaintiff, the law of torts does recognize a claim against them in combination as the tort of conspiracy if:
(1) whether the means used by the defendants are lawful or unlawful, the predominant purpose of the defendants' conduct is to cause injury to the plaintiff; or,
(2) where the conduct of the defendants is unlawful, the conduct is directed towards the plaintiff (alone or together with others), and the defendants should know in the circumstancethat injury to the plaintiff is likely to and does result.
It is under subsection (1) that I am claiming damages. It is not that the actions of those who injured me were of themselves illegal. It is that the predominant purpose of their actions was to injure me...or more precisely, that the predominant purpose of the conspiracy was to injure me.
Because it is not enough for me to show that each of the defendants individually wished to do me in. That in itself does not establish my cause of action. I must show not only that they acted to damage my interests, but that they did so with common purpose and agreement. It is not necessary for me to show that every individual defendant knew of or agreed with all of the actions against me. If a co-conspirator was linked only to one other co-conspirator, he is still a part of the conspiracy, even though his actions were limited. He doesn't need to know the full extent of the conspiracy.
There are several defences against the tort of conspiracy, and my opponents will most likely argue each one. They will probably argue that their individual actions were taken independently without knowledge of the intentions of the various other parties. They will undoubtedly argue that their actions were motivated primarily by a desire to protect the best interests of the students of Gordon Bell, and not to damage me personally.
I think they're going to have a hard time making those arguments stick.