(U.S. Information)
The only way you could get in trouble is if you built the laser and sold it without FDA accession registration particularly if it is Class 3B or higher. If that is the case and the person injures someone or themselves you could be arrested, or heavily fined for providing unlicensed laser systems to the public in violation of FDA regulations. That then opens the door to civil litigation from the victims.
Statements such as "we are not responsible for what you do with this product" are only defensible when the defendant has provided the components to the plaintiff within the bounds of the law.
Keep in mind that if you buy a 200mW 532nm laser pointer from some company, for example, and resell it on ebay when you get bored with it, you can be fined for selling it as well as open yourself up to civil litigation. Laser pointers that are greater then 5mW output (Class 3B or higher) do NOT have FDA accession numbers because the units lack the required safety features required on all 3B and 4 laser systems. That is why you see them shipped as light pens or flashlights or LED pens, etc. They are shipped with falsified customs documentation (a felony) to minimize the chance customs inspectors will select that shipment and it totally bypasses the FDA inspection. If you get caught, the FDA and customs won't go after the original seller as these guys are in China. They just file complaints and watch for imports from that company. They will, however, make an example of you since you are right there in front of them, so to speak. Most of the time they just confiscate the laser and you are out the money but with the rise in laser flash-blinding I'll guarantee someone will be made an example. Be careful it's not one of you guys.