Rights to a trademark can be acquired by being the first to use the mark in commerce or by being the first to register the mark with the U.S. Patent and Trademark Office. Bell's did not fulfill the second option, as far as we know, and therefore must rely on the first.
Under the first option, the mark must first be used in commerce, which it was. Secondly, the mark may qualify for protection (and can be registered) only after it has acquired secondary meaning (secondary meaning directly describes, rather than suggests, a characteristic or quality of the underlying product). A descriptive mark acquires secondary meaning when the consuming public primarily associates that mark with a particular producer, rather than the underlying product, and this is really only applicable in the areas in which the product is available. Furthermore, Bell's only uses the slogan on bumper stickers and not on the products or websites, which weakens Bell's argument.
The debate at the U.S. Patent and Trademark Office will hinge on the comparison of Bottling Innovation and Innovation Brewing, how similar they are, is there possible confusion between the brands due to the similarity, does the public associate either slogan/name with one brand and not the other, where the slogan is used, etc...
However, Bell's released a statement on their website:
"We have not, and are not asking them to change their name or their logo. There is no lawsuit. We are not suing them. We have not asked them for money. We have not asked them to stop selling their beer. We are asking them to withdraw their federal trademark application. Our concern is with their United States trademark application and potential impact on our brand, which we have spent 30 years building."
In the end, they still want Innovation Brewing to stop the application process, but have at least offered to "coexist". It might be that Innovation Brewing is being stubborn as they rejected Bell's offer and asked for a large sum of money (reportedly). It might also be that Bell's is being predatory by filing a lawsuit, possibly with the knowledge they might lose, but with the knowledge that they can outlast and bankrupt Innovation Brewing during these proceedings, only to buy the trademark later for a small fee as Innovation Brewing might need any money they can get.
Lesson to be learned: Trademark as soon as possible.
Prost from Germany