Any law which fails to be clear needs to be rewritten so that the judge and his court can maintain their integrity as the arbiter of right and wrong. You can't punish wrongdoing if popular opinion is divided.
What do you think is a reasonable law, in this case?
No law at all, it would certainly be more exciting. More creative. More competitive.
This sounds good until you realize that "exciting" means that the "Coca-Cola" can you just bought has something else inside (maybe seawater), because they cannot defend the brand so everyone can use the name and the color to sell their own product.
Great - people would start drinking fruit juice instead :-)