Those convicted of crimes against "sexual integrity", terrorism, high treason, espionage and other "particularly grave crimes" are exempt.
Russian lawmakers adopted a bill on Wednesday allowing ex-cons and those currently serving prison sentences to join the ongoing invasion of Ukraine.
The new measure, passed in the first reading, would expunge the criminal records of those participating in the Russian armed forces in future mobilisations, following their dismissal from service or "receiving an award".
Until now, Russian law explicitly forbade the Ministry of Defence from entering into contracts with people who have an active criminal record or are incarcerated.
While reports indicate soldiers were being drawn from Russia’s extensive prison population to serve in Ukraine since at least the summer of last year – most of whom joined the Wagner mercenary group – this was done either extralegally or through secret presidential pardons.
Wagner stopped recruiting prisoners around February this year, who were asked to sign contracts with the defence ministry instead.
The move was interpreted by analysts as an indication of the worsening relationship between Wagner leader, Yevgeny Prigozhin, and the Russian authorities.
The new law will allow soldiers to go directly from a penal colony, prison or pre-detention centre to the frontline, with Moscow lifting a ban on conscripting ex-cons in November.
A practice that was previously done arbitrarily will now be legalised and formalised, as a result of the Duma vote.
On Tuesday, Russian President Vladimir Putin confirmed he was “signing decrees on pardoning prisoners who are part of the Special Military Operation,” according to Tass, the Russian state agency.
Russian authorities continue to refer to the ongoing invasion as a “Special Military Operation,” a term Putin began using on the eve of launching the assault and annexing parts of eastern Ukraine.
Putin said that the rate of relapse among former convicts participating in the invasion was “low”.
“Among the participants in the Special Military Operation there are relapses of around 0.4%,” he told journalists on Tuesday.
When the bill was proposed in late May, its proponents from the Duma’s Defence Committee indicated “a significant number of citizens were identified who wish to enter military service under a contract, from among those with whom a contract cannot be concluded.”
The bill features an exception for those who “have committed crimes against sexual integrity, are convicted of terrorism, high treason, espionage and other... particularly grave crimes.”
Putin said those who recommit crimes after serving in the armed forces would not be exculpated from prosecution.
The bill also now allows for those considered to be of “limited fitness” to serve by increasing the age limit of those the ministry can enter into the forces during the period of mobilisation, martial law or in wartime conditions.
For senior officers within the military, including colonel-generals and admirals, the age limit will now be 70 years, while the limit for other military ranks will now be 65 years.