The outcry by former US Vice-President Dick Cheney and John McCain over an inquiry announced into the alleged torture tactics used by the CIA to gather information from terror suspects is the mother of double standards.

According to Cheney and McCain, the probe announced by the US Justice Department, which is aimed to cleanse the reputation of the US, will diminish the morale and effectiveness of the CIA. It could be a lot worse for the CIA. The CIA agents presumably won't be tortured during the probe to ensure that they are not holding back any information.

In reality the investigation is welcome. But not just because it will almost certainly result in the downfall of a "few good men". The investigation, if undertaken thoroughly, may assist in demarcating the permissible limits of torture.

In the eight years since 9/11 the US has not been subjected to a single terrorist act on its home soil. According to Cheney "the enhanced interrogation techniques were absolutely essential in saving thousands of American lives".

So was the torture justifiable? In some instances, perhaps. Contrary to prevailing sheepish sentiment, torture is permissible in extreme circumstances.

In fact advocates of a complete ban on torture don't dislike torture enough.

They are willing to abdicate a potential means of preventing the torture and murder of innocent people in preference for an extremist anti-principle that "good guys never torture".

Torture has justifiably earned a bad reputation over the centuries. It conjures up images of people being cruelly harmed for no higher ends than punishment and domination. It is not possible to mount a respectable argument that torture in such circumstances can ever be justified.

Different considerations apply when it is used for compassionate, life-saving, purposes. Every society throughout human history has accepted that it is permissible to kill in self-defence or defence of another.

If we can kill to protect others, it is nonsense to suggest that we can't inflict lesser forms of harm, including torture, to achieve the same result.

Life-saving torture has the same moral justification as other practices where we sacrifice the interests of one person for the greater good. With life-saving compassionate torture the pain inflicted on the wrongdoer is manifestly outweighed by the benefit stemming from the lives saved. The fact that wrongdoers don't expressly consent to their harsh treatment is irrelevant. Criminals and enemy soldiers don't consent to the pain inflicted on them either, yet we're not about to empty our prisons or stop shooting enemy soldiers.

The most common objection to torture is that it doesn't work. People who are tortured supposedly don't fess up accurate information. If this is right, then we should disavow torture, even as a self-defence mechanism.