Rebecca Tushnet has an excellent post on SCOTUSblog that asks: Following the MGM v. Grokster decision, just what may technology companies safely say in their ads, press releases, and the like? And what statements should they avoid, for fear that a jury will eventually find that the statements provide "evidence of stated or indicated intent to promote infringing uses"?
Or say that the same rule ends up being applied to distribution of other products. (Right now it's just a copyright law rule, but courts often create such rules reasoning by analogy; the rule might prove influential in other fields as well.) You're an alcohol manufacturer. You know that some of your product is consumed by underage drinkers. You make money from them, because there's no way you can avoid it.
Most of your buyers use the alcohol legally, not illegally, so in this respect you're likely different from Grokster; but while the Supreme Court discussed how much of Grokster's user base was likely violating the law, intentional promotion liability can apply without regard to whether most users are illegal — intentionally promoting illegal uses by even a minority of users could lead to liability for those uses. What can you safely put in your ads, and what might lead to liability on the theory that it shows an intent to promote underage drinking (even if you personally know you have no such intent)? Remember that the intent needn't be expressly "stated," but may simply be "indicated," as it is in Grokster itself.
Likewise if you're a gun manufacturer. You know some of your guns — a small fraction, but some — are used by violent criminals. (There are about 200+ million guns in the country, and about 400,000 violent crimes using guns per year, so the great majority of guns aren't used to commit a violent crime.) You make money from all buyers, legal or illegal. What can you safely put in your ads, and what might lead to liability on the theory that it shows an intent to promote the buying of guns for illegal purposes (again, even if you know you don't have such an intent)?
UPDATE: Corrected "500,000 gun crimes" to 400,000 — I had been working from memory, and my recollection was from years when crime was higher than in 2002, the latest year for which I found data (see table 66, which reports on robberies, assaults, and rapes, both completed and attempted, and add some 10,000-odd firearms homicides). I also changed "gun crimes" to "violent crimes using guns" to better track my point, which was focused on violent crimes. No-one has any idea how common, say, pure gun law violations (from illegal concealed carry to improper storage while taking the gun to the gun range to failure to properly register) are. My concern here is with violent crime, because that's what most people are really worried about, and what gun manufacturers wouldn't want to be seen as promoting.