Cans of Pabst Blue Ribbon beer are show at the Burton & Channel Islands store in Los Angeles, May 21, 2015. Rochelle Brodin Photography | Getty Images

MillerCoors and Pabst Brewing are headed to court over a half-a-billion dollar lawsuit Pabst lodged against the Keystone beer maker. The center of the dispute is a decades-old agreement under which MillerCoors brews all of Pabst's legacy beers, including Pabst Blue Ribbon. The agreement is set to expire in 2020, but it has two options to renew. MillerCoors, facing declining volume in the U.S., has said it may not have the capacity to continue that relationship. The stakes for Pabst are high. Without that contract renewal, many of Pabst's beer brands will be orphaned. It is expensive to build a brewery and there are not many breweries across the U.S. built for the capacity a company as large as Pabst requires.

Pabst is accusing MillerCoors of breach of contract, breach of anti-competition laws, fraud and misrepresentation. MillerCoors contests those claims, arguing it has the right to determine whether it has the capacity to extend the contract. In April, a Milwaukee court judge denied MillerCoors' motion for summary judgment, which could have prevented the suit from going to trial. The two are set to go to trial in November of this year. MillerCoors, owned by Molson Coors, makes beers under labels like Coors, Miller, Blue Moon and Keystone. It last quarter reported a drop in its earnings before interest tax depreciation and amortization (EBITDA) of 12.2 percent and a decline in its volume of 3.8 percent. Pabst, which also makes brands like Old Milwaukee, is privately held and its finances could not be immediately obtained.

Competition and potential brewery closure