Forbes has the details on the decision:
The decision upholds the right of manufacturers — in this case, Swiss watchmaker Omega — to use copyright laws to prevent U.S. retailers from selling goods they obtained overseas.
SCOTUSblog has more:
At issue is the so-called “first sale doctrine.” Federal law provides that, if a copy of a protected work is made or purchased legally, that copy can be sold without the consent of the owner of the copyright. Once the owner of a protected work has sold a copy of it to someone else, that other person may sell it without permission of the owner of the copyright.
Under other provisions of copyright law, importing a copy of a protected work amounts to an infringement of the copyright if the copy was made abroad and brought back into the U.S. without permission. The first-sale doctrine is an exception to that provision. The Ninth Circuit, however, ruled that the doctrine applies only to copies made legally and sold inside the U.S. It said that recognizing the defense for goods made abroad would extend copyright law beyond U.S. borders inappropriately.
This case involved Swiss watchmaker Omega and warehouse club Costco. Costco was buying Omega Seamaster watches abroad and selling them for $1,299, about a third less than Omega’s suggested retail price of $1,999. This latest ruling allows foreign copyright holders to control how its works are distributed.
Put that another way, you buy an Omega watch and it's yours ... forever. Technically this ruling prevents you from being able to sell it on without obtaining Omega's permission, whether that be a public sale or a private one.
Now, you might not be buying or selling many Omega watches, but chances are that if you are reading this blog you're the kind of person who buys a lot of imported stuff, either directly, or imported without the direct consent or approval of the manufacturer. You could well be affected by this decision.
While this doesn't affect foreign-made products found in most peoples homes, it's a worrying development for those who value their right to do with their stuff whatever they want to do with it.