Gordon Brown has said he could overturn the recent changes to licensing laws - specifically those allowing pubs to open 24 hours a day.
The prime minister told BBC Radio 4's Today programme: "I will not hesitate to change policies if I think that we have got to make these changes."
Brown told Today there was an "issue" about 24-hour licensing.
If it needs a reversal of policy, we will do it. Just as with gambling, we will review all the evidence and if a change needs to be made, I will not hesitatePM Gordon Brown.
He added: "That's why we are reviewing it. Where there are things that are wrong and where mistakes have been made, we will look at these and we will change these things.
"That's why on casinos we are looking again, on cannabis we are looking again and that's why on 24-hour drinking we are looking again."
Asked about the impact of longer licensing hours on behaviour, he said: "I think we have got to learn. In most cases, it has not had any devastating effect.
"It is the same with cannabis. It is the message you send out.
"Why I want to upgrade cannabis and make it more a drug that people worry about is because we don't want to send out a message - just like with alcohol - to teenagers that we accept these things.
"Binge-drinking is unacceptable, bullying is unacceptable, bad behaviour in classrooms is unacceptable.
"If it needs a reversal of policy, we will do it. Just as with gambling, we will review all the evidence and if a change needs to be made, I will not hesitate to make a change in the interests of the country."
A Home Office inquiry into the subject is expected to report by the end of the year.