From midnight anyone caught drink driving will be handed a minimum three month ban.
Previously those caught with a blood alcohol level of between 50 and 80 milligrams were able to get away with 3 penalty points.
Transport Minister Shane Ross says the aim of the new laws is clear.
It's a very historic day," he said.
"I think the message has to go out absolutely clearly to people as a result of implementing this today.
"It commences at midnight tonight hope people will take the message quite clearly - 'don't drink and drive'.
"This is about saving lives, it's nothing more, it's not political, it's simply about having lower road deaths."
