It's just a photo!

There was a case a while back where a man was accused of being a paedophile for taking a photograph of a young girl in a swimming costume at a swimming baths.  In the event it turned out that she was a relative of his whom he had taken swimming there and he had taken the photograph to show her family, so no action was taken. But it did raise the question - is a photograph of a young girl in a swimming costume potentially child pornography?  The argument is that there may be - probably are - those who would view such a photo for sexual gratification.  So which is the determining factor - the reason it was taken or the use to which it might be put?  A judgment in a recent case in Texas has come down firmly in favour of the first of these.  This is America of course, and so the case was decided on the basis of their First Amendment which protects freedom of expression, but there is no doubt it was a sensible decision as otherwise you are holding the creator of any sort of image responsible in law for whatever illegal use it may be put to, which should clearly only be so if it was created specifically for that purpose.