A shareholder's rights plan can be implemented after a takeover

bid is announced

Many jurisdictions other than the U.S. view the poison pill strategy as illegal, or place restraints on their use.

In Canada, almost all shareholders rights plans are "chewable", meaning they contain a permitted bid concept such that a bidder who is willing to conform to the requirements of a permitted bid can acquire the company by take-over bid without triggering a flip-in event. Shareholder rights plans in Canada are also weakened by the ability of a hostile acquirer to petition the provincial securities regulators to have the company's pill overturned. Generally the courts will overturn the pill to allow shareholders to decide whether they want to tender to a bid for the company. However, the company may be allowed to maintain it for long enough to run an auction to see if a white knight can be found. A notable Canadian case before the securities regulators in 2006 involved the poison pill of Falconbridge Ltd. which at the time was the subject of a friendly bid from Inco and a hostile bid from Xstrata plc, which was a 20% shareholder of Falconbridge. Xstrata applied to have Falconbridge's pill invalidated, citing among other things that the Falconbridge had had its pill in place without shareholder approval for more than nine months and that the pill stood in the way of Falconbridge shareholders accepting Xstrata's all cash offer for Falconbridge shares. Despite similar facts with previous cases in which securities regulators had promptly taken down pills, the Ontario Securities Commission ruled that Falconbridge's pill could remain in place for a further limited period as it had the effect of sustaining the auction for Falconbridge by preventing Xstrata increasing its ownership and potentially obtaining a blocking position that would prevent other bidders from obtaining 100% of the shares.