iPhone application creator Hottrix is suing the brewer and ad agency for apparently ripping off its "iBeer" iPhone application and creating their own version called "iPint".
According to the lawsuit, Beattie McGuinness Bungay contacted Hottrix in order to license its iBeer application and the accelerometer technology that causes the virtual beer to appear as its being drunk as the phone is tipped.
Hottrix rejected the proposal and Beattie McGuinness Bungay created its own version -- iPint -- using Illusion Labs, a Swedish technology company.
The iPint application was free, costing nothing but exposure to Coors brand Carling, where as Hottrix iBeer app cost iPhone users $2.99 (£1.70) per download.
The lawsuit said: "As iPint increased in popularity, iBeer 2.0 decreased in popularity since end users could get ostensibly the same application without a direct cost -- besides viewing the Carling advertising -- of paying $2.99 for iBeer 2.0"
When iPint appeared in Apple's App Store, it quickly became one of the most downloaded free applications and won the Silver Cyber Lion award at Cannes earlier this year.
The iPint application also included a Carling themed game called Barslide where users guide a sliding beer down the bar in order to win a prize -- a virtual beer. In the lawsuit, Hottrix said the game was nothing more than a cover to hide the fact its iBeer application had been ripped off.
Hottrix sent a "cease and desist" request to Beattie McGuinness Bungay and informed Apple of the infringement. Apple responded by removing iPint from the Apple store in the US, although it still remains available for download internationally.
After iPint was removed from US Apple stores, iBeer quickly became one of the most popular paid-for applications, however, because the iPint app still remains available to international iPhone users, Hottrix estimates loss of profits to be worth $12.5m.
Jason Fisher, the lawyer representing Hottrix said: "Hottrix is a small 'mom and pop' company that takes the protection of its intellectual property very seriously."
Molson Coors and Beattie McGuinness Bungay were both unavailable for comment.
Beattie McGuinness Bungay, the agency co-founded by Trevor Beattie, was in the process of being acquired by Omnicom-owned TBWA\ before talks suddenly fell apart last week.