I hate to say it, but daniel raises some relevant points in his comments in terms of trademark. The main point is that Warner Bros owns a number of trademarks on “Soylent Green.” Though “Soylent” is different from “Soylent Green” WB might still have a basis for legal action.
If the case were to go to court, the issue would probably come down to the question of the likelihood of confusion. In other words, would a person think upon seeing a product labeled “Soylent” that it’s associated with the film “Soyent Green” or WB? Unfortunately, courts have generally used a pretty low standard, usually called the “moron in a hurry” standard, which is to say if a person of low intelligence with no time to think about it were not to confuse two similar trademarks, then there’s no likelihood of confusion (instead of using the higher so-called “rational person” standard).
Considering these things, I think Rob is unlikely to win a suit if WB were to press it. Even if he is granted the trademark by the USPTO, I don’t think it’ll change anything. And, even if he were to win, is the trademark really worth the legal fees and time?
Of course, WB may never press it. The Soylent Green trademark is old property for WB, and not a particularly valuable one. The copyright on the movie and the book it’s based on are still moderately valuable, but we’re talking trademark here and since companies aren’t out there hocking a whole lot of Soylent Green products, it doesn’t have much value.
This means it’s possible that Rob could just continue with the name, waiting for the legal nastygram from WB that may never come. The downside with this is that, should WB try to play trademark bully after Rob’s product is established and he’s got name recognition, it could hurt the company, since he’ll have to build up name recognition on a new trademark. For that reason, personally, I’d try to change the name now. Us DIYers can continue to call it Soylent with no concern for trademark infringement (unless we try to sell our soylent), but I think the product Rob brings to market should be call like “Nom,” or “Vida” or “Chi” or whatever name he likes.
On the other hand, he could contact WB’s legal department and try to work out a licensing arrangement, but, again, you have to ask whether it’s worth it. I don’t think it is.
As to issue of stealing other people’s intellectual property, which daniel brings up a few times, he’s confusing copyright and trademark. Aside from the fact that “stealing” is an inappropriate metaphor for intellectual property since ideas are non-rival goods, Rob is not making illegal copies of either the book or the movie and selling them. The copyright on Soylent Green and Make Room! Make Room! are both secure and the relevant people continue to make money off of these. Trademark and copyright are two very different things. If you’re going to haughtily lecture people on legal issues, you might want to first get a grasp on these very basic legal concepts.