Groups protesting former President Bush's visit were threatening to throw shoes at him, a reference to a notorious 2008 incident.

Getty

ormer President George W. Bush was forced to forgo a planned trip to Switzerland this week as human rights activists exerted growing pressure on the Swiss government to arrest him for allegedly sanctioning "the torture of terrorism suspects" held at Guantanamo Bay, Cuba. Left-wing protesters even threatened to file a criminal complaint against the former president. Here, a brief guide to the controversy:

Why was Bush heading to Switzerland?
Bush was slated to be the keynote speaker at a February 12 Jewish charity gala in honor of the Switzerland-based United Israel Appeal.

What were the activists planning to do?
Groups including Amnesty International, the Center for Constitutional Rights, Human Rights Watch, and the International Federation of Human Rights said they would file a 2,500-page complaint against the president under the international Convention Against Torture. Two men supposedly inspired the complaint: Majid Khan, who is reportedly still at Guantanamo, and Sami al-Hajj, a former Al Jazeera cameraman, who was released in May 2008. Organizers were also planning protests outside the hotel where Bush was going to speak, and were urging demonstrators to bring shoes to the rally, a gesture intended to evoke the Iraqi journalist who threw his shoe at Bush in 2008.

Could Bush really have been arrested?
It's unlikely. An "initial assessment" by the Swiss Justice Ministry determined that the former president would have immunity from prosecution for his actions while in office, a ministry spokesman told The Associated Press. The activist groups disputed that. But even if Bush could have been brought up on charges, prosecutors would likely have run out of time to investigate them and take action before he left the country.

So why was his appearance canceled?
Representatives of the charity say security fears, not legal threats, led them to cancel Bush's appearance. "We regret that the speech has been canceled," a Bush spokesman told The Associated Press. He said the president "was looking forward to speaking about freedom and offering reflections from his time in office." But the groups seeking Bush's arrest question these official statements: "Whatever Bush or his hosts say, we have no doubt he canceled his trip to avoid our case."

Sources: Associated Press, CBS News, Washington Post, Reuters