Two St Louis (Missouri, USA) craft beer producers have settled their trade mark litigation over the use of a lightbulb on tap decals and other marketing collateral.
 As would have been expected by anyone familiar with TM law, the brewer with the trade mark registration triumphed.
 Side Project Brewing opened in 2013, and filed to protect its name + logo that year:

Modern Brewery opened the following year, but the owner claimed he had “come up with the lightbulb design years before we ever brewed a drop of beer”, and also claimed he had several conversations with Side Project’s founder before either brewery opened.  He said the cost of litigation was why he settled.
The moral of the story is you need to file for trade mark protection as soon as possible.

See http://bit.ly/2xaVaIj for a local press report of the settlement.

Australian Beverage Trade Marks’ founder, James Omond, discusses the ins and outs of trade mark protection for independent brewers with Matt Kirkegaard and James Atkinson in the ‘Beer is a Conversation’ podcast – listen below, or check out the Brews News website at: 
https://www.brewsnews.com.au/2017/09/29/beer-conversation-james-omond/
​You can also download the podcast for later consumption!