The Western Mail has a report about a Drug Testing being demonstrated to Members of the Welsh Assembly, and catching out the two main Assembly Member proponents of the £40,000 Ion Track narcotics detection machine with "false positives" for THC/cannabis.
"Edwina Hart, social justice minister for Wales, tested positive for cannabis after her hands were swabbed using a special cloth.
She said, "You could pick it up anywhere, couldn't you?
"It could come out of cash, a cash-point, a beer mat, or anything else.
"It is a very sophisticated system that can pick up anything, if you have been in contact with someone's jacket or anything."
Conservative AM William Graham organised the demonstration using the first machine introduced to Wales, which is owned by Gwent Police.
But even he was shocked to test positive for THC, the chemical found in cannabis. "Good gracious, where the dickens could I have got that from?" he asked."
"PC Simon James, crime prevention officer, said that it showed there was no place to hide.
"The major use will be in nightclubs and drug dealers would be an idiot to come into a club with this machine in there.
"It is a deterrent and preventive measure really. In Gwent we have a hit-list of 10 pubs and can use this machine to do swabs on tables, chairs and narrow things down to improve our intelligence.
"It can be used to search houses. For example in some parts of the UK where there is a problem with crack cocaine they have swabbed microwaves and found traces."
PC James denied that this machine casts suspicion on everybody, and that it is not subjective enough.
"The way we interpret the readings plays a big part, as does the way a person reacts if found with traces of drugs on their hands," he said. "We can adjust the sensitivity and exclude certain drugs depending on how the machine is being used.""
That does not seem like a foolproof way of ensuring that there are no false accustions , like with the Welsh Assembly Members.