Olivia Jenkins, defence counsel for Marcus John Williams, said her client was in custody at the Launceston Reception Prison because Risdon Prison was overcrowded and had staffing issues.

She told Justice Robert Pearce that he had spent most of that time in his cell.

He was allowed one hour a day in the yard which was an underground concrete area that had no access to sunlight or open air.

IN OTHER NEWS:

Lockdowns, every day last week, meant the hour in the yard was not available, she said.

Ms Jenkins said that the lack of fresh air and sunlight had affected the mental health of her client who had since been diagnosed with depression.

She submitted that the restrictions meant the Launceston Reception Prison was a more punitive punishment than Risdon Prison.

Justice Pearce asked Crown prosecutor John Ransom to check the assertions in the submission.

He said that a check should be made before he took the submission into account in sentencing.

Ms Jenkins' submission comes after the Custodial Inspector Richard Connock's report last week found that the Tasmanian Prison Service consistently failed to meet its own legislative and human rights obligations.

The report said there were 605 lockdowns in December last year.

A Department of Justice spokesman said the Launceston Reception Prison was not designed to be used for the long-term accommodation of prisoners.

"It is primarily used for short-term accommodation for prisoners before moving to a longer term more suitable facility," the spokesman said.

"The average time out of cell per prisoner per day in the Launceston Reception prison does vary, but was averaged over seven hours between March 2021 and May 2021.

"The TPS also aims to deliver prisoners as much time in the open air as possible, while balancing the need to keep staff, visitors, and other prisoners as safe as possible."

The spokesman said the state government's investment in both staff and infrastructure resulted in the prison being under capacity in most areas.

"As at May 25, 2021, the statewide prison capacity was 755. The overall prison utilisation rate was 89 per cent," the spokesman said.

They said the capacity of the Risdon Prison Complex was 352 and that there were 296 prisoners in custody as of June 25.

"Prison management continues to explore a variety of other strategies to minimise the likelihood of lockdowns in Tasmanian Prison facilities, and takes a planned and structured approach to the use of lockdowns in order to minimise their effects as best as possible," he said.

The spokesman said the government was upgrading and building the necessary infrastructure, as well as recruiting staff at a rate never seen before' to address capacity issues.

"The government is also currently constructing a $85 million Southern Remand Centre on the Risdon Prison site to modernise the state's correctional facilities and addressing future capacity and rehabilitation needs," they said.

"Construction of the Southern Remand Centre is on track to be completed by the end of this year with full operation expected in early 2022 following a commissioning period.

Mr Williams, 35, pleaded guilty to being in possession of a firearm when he was subject to a firearm prohibition order.

He will be sentenced on Thursday, July 1 at 4.15pm.