BORIS Johnson visited Croydon Magistrates' Court today to unveil a new scheme to tag drunken offenders with ankle bracelets which can tell if they've been drinking.
From today, justices in South London can order offenders to remain sober and wear the "tag" which measures the alcohol in their sweat.
He was joined by Croydon and Sutton London Assembly member Steve O'Connell who himself donned the device over two days for a test run.
Mr Johnson joked that Mr O'Connell's results showed "basically, almost continuous alcohol consumption".
But he said the tags had been successful in tackling alcohol-related crime in America.
"The argument is when you get people who are convicted of alcohol related offence, a Saturday night fight or whatever, where a custodial sentence is clearly not appropriate, what you want to do is to stop them drinking."
The first order forcing an offender to wear the tag was passed at Croydon Magistrates' this morning.
Mr O'Connell said the tag had been "barely noticeable" during the day, but had proved a bit more of a nuisance at night as it buzzes every 30 minutes to check alcohol levels.
"It was a good test really, I said I'd do it because I knew I was going out for a drink with friends. I had three pints and it showed up on the graph.
He added:"The pilot lends itself to Croydon because town centres throughout the borough may well have alcohol related problems.
"I hope it will prove successful and it can only be a good thing for Croydon and Sutton if it drives down alcohol-related violence."
Around 150 offenders are expected to be forced to wear the tag for up to 120 days as part of the trial, which is taking place in Croydon, Lambeth Southwark and Sutton.
If an offender breaches the sobriety order, they will be brought back before a judge or magistrate who can consider further punishments.
Alcohol related crime is estimated to cost the UK between £8bn and £13bn every year.
According to Public Health England, alcohol-related crime is significantly higher in London than all other English regions.
