The Tribunal may act to prevent businesses that have a large market share from taking actions which are anti-competitive and are likely to have the effect of substantially lessening competition. The Tribunal can act against firms, for example, which refuse to supply their products in an attempt to deprive one of their customers of an essential product. The Tribunal can also act to prevent someone from refusing to supply a product unless the customer only buys from one supplier and, under some circumstances, the Tribunal can act to prevent a firm from attempting to limit the market in which a buyer may re-sell the product. The Competition Act makes it a criminal offence to participate in an agreement that seeks to lessen competition unduly. There need not be a formal agreement.
Conviction can arise from informal agreements.
In fact, the courts are entitled to infer an agreement if no evidence of a direct agreement is given by the prosecution. The act also creates a civil right of action for anyone who sustains damages from the conspiracy. Conspiracies are prosecuted quite aggressively in Canada, with fines in the millions of dollars.