As I wrote in a column in November, people will soon be able to download files of physical objects and print them out at home. Although being able to print out a new mug or toothbrush at home sounds magical, I said that there would surely be copyright problems that occur as a result of this technology’s going mainstream.

This theory struck oil this week when the Pirate Bay, a notorious peer-to-peer file-sharing Web site that is a source of free copyrighted music and movies, said it was creating a new download section on its site that would enable people to freely take files a 3-D printer can recreate into physical things.

In a blog post, the Pirate Bay Web site declared its entrance into a new copyright battle thusly: “We believe that the next step in copying will be made from digital form into physical form. It will be physical objects. Or as we decided to call them: Physibles.”

Physibles? O.K. But what makes the declaration by the Pirate Bay different from other copyright issues is that some of the objects people upload to the site — and others then download — might not actually break copyright laws.

In my November column, titled “The 3-D Printing Free-for-All,” I spoke with Michael Weinberg, a senior staff lawyer with Public Knowledge, a Washington digital advocacy group, who explained that copyright law did not always apply to recreating physical objects.

Mr. Weinberg said that because of old copyright rules, recreating an object that is considered “useful” is not actually a copyright violation. “If an object is purely aesthetic it will be protected by copyright, but if the object does something, it is not the kind of thing that can be protected,” he said in the interview. A useful object may be patentable, but we are talking about copyrighted plans.

Of course the Pirate Bay isn’t the first Web site to offer the ability to download files that can print objects. Web sites like Thingiverse, a free online site that offers schematics of more than 15,000 objects, have been around for some time. The announcement by the Pirate Bay will bring this issue a lot more scrutiny and, I dare say, heated talk.

As a result, we could be on the verge of a new series of legal battles centered on people who download 3-D files.