The program is capped at 20 participants and the Justice Department said the waiting list had gone from 13 to six offenders.

Last week a Launceston lawyer said his client was told he could wait up to 17 months to get into the program.

Another practitioner told the magistrate that the wait was "so long you might as well not have it [the program]".

" Members in Launceston are telling me that many of their clients who are eligible are taking the option of going to prison rather than waiting for a place to be made available on the program," society president Anthony Mihal said.

He said the cost of the program was significantly less than the estimated $140,000 required to house a prison inmate per year.

Offenders can only enter the program if their crimes are drug-driven and they would otherwise serve time.

Violent and sex offenders are prohibited.

Those that fail the program are liable to be resentenced to prison.

"The program is not a soft option. It is rigorous and time consuming. It is a two- year intensive program during which the threat of imprisonment is hanging over the offenders head," Mr Mihal said.

"If the program achieves its aim and rehabilitates an offender whose drug addiction is a factor in his or her offending, the likelihood of reoffending should be greatly reduced."

Mr Mihal said for those who end up in jail instead the recidivism rate was about 60 per cent.

The Justice Department, which administers the program, would not confirm waiting times to access the program.

Statewide it received $1.5million in funding this financial year.

Offenders are now fully assessed up front so they don't linger on a waiting list only to be knocked back from the program, a department spokeswoman said.

This was not previously the case.

"Magistrates will also be advised of the anticipated wait time for offenders that are assessed as both eligible and suitable, to assist in avoiding backlog and delay," she said.