Police Association president Greg O'Connor said the pre-charge warning system was a response to a Government instruction to reduce the number of people going into the criminal justice system.
"The consequence will be a generation growing up with no fear of consequences and they will behave accordingly."
He said going to court acted as a deterrent, even if sentences didn't.
"Now it's just a bit of a nuisance to get arrested."
He thought the Government would take another look at its targets and predicted police would start instructing frontline officers to charge more people in the not too distant future.
"I think what will happen is that, in future, police strategies will go the other way. They'll say 'no we're going to arrest people and we're going to put them before the courts, we're going to keep them in the cells'. Because they'll realise that police don't arrest people for the fun of it, they arrest them because there's a need."
Mr O'Connor said the pre-charge warning system had been initially effective - before the criminals caught on to it.
Nationally, 62.1 per cent of offenders ended up before the courts in the year to July 31.
Figures showed 37.1 per cent of offenders were dealt with through non-court action nationally and the remaining cases didn't proceed.
Nationally, just one in eight public order offenders and a third of abduction, harassment and related offenders were dealt with in court. Less than half of those committing theft and related offences were dealt with by courts.
A police spokesperson said fewer offenders were now being dealt with through the courts for public disorder, harassment and theft due to the introduction of pre-charge the warning scheme in 2010.
A pre-charge warning was a formal warning given after arrest for a comparatively minor offence. It was one way of reducing court time for low-level offending, while ensuring crime was still addressed and victims were supported, said police.
They differed from traditional, more informal warnings given in the field, where the offender was not arrested. A pre-charge warning was issued in writing at the police station after a person had been arrested for a qualifying offence.
To be given a pre-charge warning, offenders needed to be 17 years of age or over and to have committed a low level or minor offence with a maximum penalty of six months' imprisonment.
Those committing family violence and methamphetamine offences were ineligible for a pre-charge warning, said police.
Police considered multiple factors when dealing with offenders through non-court action, including behaviour and attitude, type of offence, severity, availability of options, wishes of any victim, evidential threshold and offender history.
The police figures record unique offenders. Unique offenders are individual offenders counted once in the year regardless of how many times they have been dealt with by police.
