Barack Obama's amazing sense of balance on the moral high-wire of American politics has been tested over the past few days. Last week he reversed his decision to accept a court order to release photographs depicting the abuse of US-held prisoners in Iraq during the Presidency of George W Bush. Many of his supporters on the left expressed their sense of betrayal at this volte-face.

Two days ago, however, Obama regained the admiration of those who in America are termed "liberals", by reaffirming his strong support for abortion rights during a graduation speech at America's leading Catholic University, Notre Dame. This took courage on the President's part; as junior senator for Illinois, Obama had even opposed legislation to protect children who are born alive after an "unsuccessful" abortion. No wonder he faced a barrage of heckling at Notre Dame – which he dealt with in his usual elegant manner.

In terms of American politics these two initiatives don't seem to hang together at all: we might expect that the sort of people most scandalised by the President's giving way to CIA pressure over the release of the "torture images" would applaud his rebuttal of the anti-abortion activists. Yet there is another way of looking at this. With a prescience verging on the eerie, Mike LaBossiere of The Philosopher's Magazine has recently written a piece entitled "Abortion and Torture". Dr LaBossiere looked at the arguments for abortion and torture – and found that they have much in common.

Those in the last US administration who advocated the use of what they euphemistically termed "enhanced interrogation techniques" – and the media commentators who backed them – argued from a strictly utilitarian point of view. Just as the pro-choice campaigner insists that no woman ever undertakes an abortion with anything other than a heavy heart so the former vice-president Dick "Dark Side" Cheney would equally insist that "enhanced interrogation techniques" were not in themselves a good thing.

His argument is that such interrogations were a lesser evil than the harm they sought to prevent – a planned terrorist outrage which might otherwise not be detected. Similarly, the advocate of a woman's absolute right to abort at any stage in her pregnancy will argue that unpleasant as a third-trimester abortion is, it causes less misery than "bringing an unwanted child into the world".

There are, of course, differences between these two events. For example, the CIA employed waterboarding – under the ludicrous and self-serving legal pretence that it was "not torture" – on only two men that we know of: Khalid Sheikh Mohammed and Abu Zubaydah. These are both people involved in a terrorist organisation committed to mass murder. By contrast, the target of abortion is a person – or pre-person – who is as innocent of harm as anyone can be. The risk such a life-form presents is only that of growing to full term, and thus being born.

There is a second difference, equally obvious. The target of the abortion is eliminated altogether, whereas the CIA deliberately chose a method which causes no visible physical damage to the sufferer, with doctors in attendance, just to make sure – as they were when the Spanish Inquisition practiced an identical method of interrogation.

Some anti-abortion campaigners would add to this that the foetus feels extreme pain as he or she is "terminated". Nobody knows for certain at what stage the unborn child feels pain – we don't recall our experiences in the womb – but it is visibly clear that at a certain stage in pregnancy the foetus will physically react to certain stimuli (such as the insertion of a needle).

The most passionate proponents of abortion rights tend to argue that the unborn child is not really a human at all. "It" might have a cerebral cortex and a beating heart, they admit, if pushed – but these attributes are not enough to guarantee "it" any moral status. They argue that the unborn child has no status other than being "wanted" or "not wanted" by the mother. So just as there is no law against people destroying their own possessions, however valuable others might think them, the foetus, in this view, is equally the mother's to do with as she wishes, whether to cherish or destroy.

This depersonalisation of the unborn child is tellingly similar to the view of terrorist suspects taken by those who advocated barbaric interrogation practices – and I should remind readers that three years ago in this column I described the American government officials who authorised it as "using Gestapo tactics in the name of freedom" and of "behaving like secret policemen in a two-bit dictatorship".

The American Constitution guarantees those foreign terrorist suspects the same fundamental right not to be tortured in US custody as any American, based on its framers' belief that the very act of being human entails certain "inalienable rights"– which is why George Bush and Dick Cheney are vulnerable to prosecution.

This explains why those associated with the "enhanced interrogation techniques" argued so fiercely with Obama that photographs of the victims under interrogation not be released. It is when people actually see the evidence that they fully understand what is involved, and how degrading it is, not just to the sufferers, but to the nation carrying out such practices: that was why the leak of pictures of Abu Ghraib prisoners being abused caused such a furore back in 2003. For many people, only the image triggers empathy.

In the 2001 General Election, the Pro-Life Alliance produced a film showing shocking photographs of abortions, revealing the human detritus that results from the procedure; but none of the television companies would allow the film to be broadcast, on the grounds that it would "offend against good taste and decency". I had a degree of sympathy for that decision, since I am not a fan of snuff movies – although the court of appeal later ruled that the TV companies had engaged in censorship. "Shocking though the images are," the court said, "they represent the reality of what is involved in the abortion process."

The most powerful argument for abortion rights is privacy – the right of the mother not to have the contents of her womb the subject of legal injunction. Dick Cheney takes an exactly similar view about what went on in Abu Ghraib.

d.lawson@independent.co.uk