fascinating.

Drug War Chronicle
Europe: British Prisons Install Methadone Vending Machines
In a bid to promote opiate maintenance therapy behind bars, the British government has begun installing methadone vending machines in the country's prisons. Justice Minister Phil Hope told parliament last week that 57 vending machines have been installed so far.
The machines allow prisoners to receive an individualized dose of methadone by giving a fingerprint or an iris scan. The machines are paid for by the Department of Health and will cost about $6.5 million dollars, about 10% of the department's prison drug treatment budget. The target is to have the machines in half of Britain's 140 prisons.
According to the latest available prison population statistics, in 2007, nearly 6,400 of Britain's 81,000 prisoners were there on drug charges, with slightly more than half of them charged with simple drug possession or possession with intent to distribute. The official statistics provide no breakdown of which drugs were involved.
"Methadone dispensers are a safe and secure method for providing a prescribed treatment," said a health department spokesman. "They can only be accessed by the person who has been clinically assessed as needing methadone and that person is recognized by a biometric marker, such as their iris."
Providing methadone to addicted prisoners allows them to manage their habits without resorting to illicit heroin supplies within the prisons. But the opposition Conservatives were quick to try to score political points, claiming that the Labor government would rather "manage offenders' addiction" than end it.
"The public will be shocked that Ministers are spending more on methadone vending machines than the entire budget for abstinence based treatments," said Dominic Grieve, the Conservative shadow justice secretary. "Getting prisoners clean of drugs is one of the keys to getting them to go straight. We need to get prisoners off all drug addiction -- not substitute one dependency for another. The government's approach of trying to 'manage' addiction is an admission of failure."
The Conservatives are hammering away at Labor any way they can as they prepare for national elections sometime in the coming months. Attacking enlightened approaches to inmate drug addiction is just another arrow in their "tough on crime" quiver.

According to multiple articles on the subject, the main advantage of machines is that they obviate corruption.