The National Addiction Centre says it's written to the Government seeking reassurance that a free trade deal won't work against tougher alcohol laws.
New Zealand is taking part in negotiations for the Trans-Pacific Partnership Agreement.
It has been reported that leaked documents suggest New Zealand has agreed to a condition that would allow foreign companies to prosecute the Government if they believed the agreement had been violated.
The National Addiction Centre says it's concerned that could allow international alcohol companies to fight any attempts to change New Zealand's laws on drinking.
Auckland University law professor Jane Kelsey talks to Firstline's Rachel Smalley - watch the video.
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