Dow's 23-year-old son Matthew was killed in a crash with a woman who had been drinking and taking drugs before she got behind the wheel near Nelson on New Year's Eve 2017.
Dow presented a petition calling for random roadside saliva testing to Nelson MP Nick Smith last week but the petition has been reopened for a week to seek more signatures.
The Government has prepared a discussion document but it has not yet been released for public consultation despite Deputy Prime Minister Winston Peters telling Parliament last week it had been signed off by Cabinet last September.
National claims the Government sat on proposals from police and transport officials for 17 months.
Dow and Smith also claim Police Minister Stuart Nash misled them when he told media in December last year that Cabinet had approved the discussion document and it would be released early in the new year.
Bridges told reporters today the families wanted action.
"We don't want to wait. We don't want to wait 17 months from a discussion document to get to action," he said.
"I know Karen, and the Porteous and the Keene families joining her, want to reopen the petition. They thought what was going to happen was Minister Nash was going to act and there would be action. That's what he said but that hasn't happened."
Logan Porteous, the son of Ian and Rosalie Porteous, told reporters the Government could act quickly on legislation, as it had on banning guns.
"We just hope, by putting signatures on Matthew's petition which we do support, that something can be done in the near future so that this can be stopped from happening again," he said.
Murray Keene, whose mother Ora died in the same crash, said he supported the petition.
"The numbers show, there's more people dying on the roads from drugs than drinking," he said.
Dow said she was devastated to hear about the inquest into the Waverley crash.
"There's an epidemic in New Zealand and it's a complete lottery on our roads. It could have been any one of us."
No ministers were available to comment but a spokeswoman for Nash directed the Herald to his comment last week that Cabinet had agreed to the release of a discussion document on changes to the drug-driving regime and its release was imminent.