The National Party's being challenged over how it would define gang members in its plans to crackdown on P and gangs.
Police Spokesperson Paula Bennett has announced the party would invest $82 million over four years to tackle methamphetamine use and supply networks.
Canterbury researcher Dr Jarrod Gilbert said he is concerned by National's plans to give Police new powers to search cars and houses of the most serious criminal gang members.
"On a practical level will create mayhem because who the police deem to be a gang member and who isn't deemed to be a gang member will be contested."
He said National is wrong to think that gangs dominate the drug world and that though P is a huge problem, this won't fix it.
"There's no way on earth this policy is going to have a impact on gangs or drugs but what it is going to do is garner votes,]
Dr Gilbert said the Government should focus on deterring people from meth instead.