"Of course, that is not going to be the legal position because this law change will be retrospective," he said.
Mr Bridges said up to 25 councils may have expired speed limits.
Under law changes made more than 10 years ago, councils were given responsibility for setting speed limits on all roads except those with 100km/h limits. These included roads outside schools where the speed limit dropped to 20km/h and stretches of highway where drivers were forced to slow down as they passed through townships.
Councils had to review their speed limits every five years.
"They had a legal responsibility to review those within five years and then a grace period of two years and that didn't happen," Mr Bridges said.
The minister said the Government's top legal experts looked at a range of options for resolving the issue, but it was decided that retrospective legislation was the only way to fix it.