Portman has responded by accusing the brewer of trying to “gag” the industry-funded watchdog.
Brewdog has hired London law firm Pitmans to act for it over the comments, made in a press release issued as part of a recent independent complaints panel judgement against the brewer’s Speedball ale.
Brewdog claims the comments – in which Poley said Brewdog was profiteering from drugs misuse – are defamatory and damaging to its business.
Managing director James Watt said: "Drug abuse has been a well-documented and serious problem in Fraserburgh, where we are based, and the surrounding area, so to be accused of profiteering from the misery caused by drugs is not only untrue but something that can negatively affect how people view the business."
But Poley hit back this week, saying: “Brewdog are trying to gag us from criticising this grossly irresponsible product.
“Most people will be appalled at their crass attempt to market a drink using the theme of illegal drugs.
“Instead of wasting time on futile legal action, they should concentrate on promoting those drinks we’ve not banned.”