The government has been accused of caving in to pressure from the liquor industry.
Labour says that when the Alcohol Reform Bill was announced former justice minister Simon Power said ready-to-drink (RDT) mixes would be regulated and limited to five per cent alcohol content with no more than one-and-a-half standard drinks in a can.
His successor, Judith Collins, changed the bill and is allowing a voluntary code to be developed with a safeguard that regulations can be made if and when they are needed.
Labour's Phil Goff says surveys have shown that RTDs, also known as alcopops, account for 70 per cent of the alcohol consumed by girls aged between 14 and 17.
"The government said it was `particularly concerned' about RTDs, it said it was targeting them," he said in parliament on Thursday.
"Then along came the liquor industry and told Judith Collins `we're making good money out of this, you can't restrict it and you should back down'.
"And to her shame Judith Collins backed down - that's not just shameful, it's gutless."
The bill's committee stage is being debated, when every clause is examined, and Mr Goff has put up an amendment which would limit the alcohol content of RTDs in line with Mr Power's original intention.
The legislation is due to complete its committee stage before parliament adjourns next week for the summer break.
It introduces a raft of changes to the liquor licensing regime but doesn't impose a minimum price on drinks, which opposition parties say is the only way to curb binge drinking.