Young Scottish soldiers caught taking illegal drugs may not be dismissed if they can prove they were “led astray”.
The army confirmed that, in rare cases, armed forces personnel are let off with the consumption of banned substances if they can show they are not habitual users.
The policy has been revealed as a Courier freedom of information investigation found that more than 100 army, navy and RAF recruits have tested positive for drugs at high security military bases since 2013.
Screenings were carried out at sites including Arbroath, Rosyth, Leuchars and Faslane.
A spokeswoman for the army said any serviceman or woman allowed to stay on after testing positive would be made to take a course of drugs counselling.
She added: “If you have any rank whatsoever (from Lance Corporal upwards) this does not apply.”
Despite undertaking almost 20,000 army and navy tests in two-and-half years, the MoD refused to confirm whether a single serviceman or woman had been dismissed for the offence.
However the body did say it would be usual practice for an “administrative discharge” to take place unless, in rare cases, the soldier was very young and could prove they had been “led astray” and were not a “habitual user”.
The MoD could not provide statistics for the number of RAF tests carried out.
Army figures showed that troops were caught under the influence 50 times in 2013 from around 7,180 tests.
In 2014 that figure dropped to 40 positve readings as the number of tests declined to 6,260.
In the first half of 2015 a total of 20 recruits were flagged up from 3,230 tests.
Last year the Royal Navy more than tripled their drug testing frequency to 1,630 from just 530 in 2013 and by the end of July last year they had already tested 690 personnel.
Troops that test positive can appeal and have their second sample tested at another lab.
If that also comes back positive then they will be dismissed.
The spokeswoman added: “We test completely randomly. You might get tested three times in three months and then not again for six months.
“You can be tested anywhere in the world, on operations, on exercise, in transit or sitting in your office.
“We test for drugs because we do not consider illegal drug use to be part of the Values and Standard required of our personnel.”