Private car parks will be unable to enforce fines they issue motorists with under a new piece of government legislation aimed at cracking down on dodgy operators.

The government will on Wednesday introduce new legislation banning private car park operators from petitioning a court to get access to a motorist's registration details and issue them with fines. These are often legally unenforceable.

Drivers will still receive fines slipped under their windscreen wiper, but if they don't pay, the private operator will no longer have an easy way of accessing their details to serve them with court action.

The legislation mostly affects car parks that have been set up on vacant blocks of land, and are not surrounded by boom gates. The government anticipates most public operators will install boom gates to ensure motorists pay.