In the midst of sentencing submissions for three members of the once-feared Brothers for Life gang, Justice Hamill was presented with an affidavit from the youngest, Jamil??? Qaumi???.

Jamil, 25, claims he has spent much of his 3?? years on remand under extremely onerous conditions, including being kept in a tiny cell for 24 hours a day and being placed in handcuffs during meetings with his lawyers.

Jamil and his brothers Farhad - the former leader of the gang's Blacktown chapter - and Mumtaz Qaumi were convicted over a string of violent crimes carried out during the group's reign in Sydney in 2013.

The crimes included the manslaughter of Mahmoud Hamzy in Revesby Heights, soliciting to murder Brothers for Life member Michael Odisho and shooting a teenage girl.

Farhad, 34, and Mumtaz, 32, are also being sentenced for organising the murder of debt collector Joe Antoun at his Strathfield home in December 2013.

The Crown has submitted Farhad and Mumtaz should be sentenced to life behind bars, while Jamil should attract a substantial prison term.

In an affidavit, Jamil said that, when housed on remand at Silverwater Correctional Centre, he is restricted to his cell 24 hours a day because there are Brothers for Life (Bankstown chapter) members in the main population.

"I cannot use the library, access common areas or education facilities or gain employment within the correctional centre," he said.

For the past two years he has been in segregation. His cell has a two-by-two metre "yard", which consists of a concrete floor with concrete walls and bars.

"It is not large enough to run and I can only walk approximately three steps before reaching the edge of the 'yard'," he said.

He is restricted to two phone calls a day, is handcuffed and locked in a "glass and metal cage" when meeting lawyers and can only receive pre-approved visits from family members.

On Wednesday, Justice Hamill said he found Jamil's complaints "extraordinarily troubling".

He called on the offenders' lawyers to provide the court with further evidence as to their incarceration and, in particular, the likelihood of such onerous conditions continuing once their sentences had been determined.

"If I have some evidence that someone is locked in a two-by-two metre cell and can only take three steps and ??? they are locked in that cell 24 hours a day and the evidence is unclear whether those conditions will continue ??? I think that is bordering on the inhumane," he said.

In considering either life imprisonment or a sentence of "incredible magnitude", Justice Hamill said he must be given more information as to the conditions in which the men would be kept.

Crown prosecutor Philip Hogan said Jamil had not always been kept under such strict conditions, and his conditions might be relaxed once he is sentenced and classified by Corrective Services.

"What, give them 50 years and just hope they are not locked in a cage for that period?" Justice Hamill said.

Jamil said he understands much of his sentence may be spent in segregation because the non-association order is unlikely to be lifted.

"I would like to be able to get a job whilst I am in custody but as I am in segregation and have non-association orders, I am unable to work. If my non-association orders are not lifted I may never be able to work whilst in custody," he said.

Justice Hamill ordered the offenders' lawyers to provide the court with further evidence about their custodial arrangements. Another hearing will be scheduled in May before sentence is imposed on June 16.

The judge noted the three brothers have chosen not to attend court on several occasions. While he said it was important the men were in court when sentence is handed down, he also noted there were concerns about the safety of Corrective Services officers involved in transportation between the jail and the court.