An addendum to Elfwreck's post from customs and border patrol.
Trademarked and Copyrighted Articles
CBP enforces laws relating to the protection of trademarks and copyrights. Articles that infringe a federally registered trademark or copyright or copyright protected by the Berne Convention for the Protection of Literary and Artistic Works are subject to detention and/ or seizure. Infringing articles may consist of articles that use a protected right without the authorization of the trademark or copyright owner or articles that copy or simulate a protected right.
Articles bearing marks that are counterfeit or inappropriately using a federally registered trademark are subject to seizure and forfeiture. The importation of articles intended for sale or public distribution bearing counterfeit marks may subject an individual to a civil fine if the registered trademark has also been recorded with CBP. Articles bearing marks that are confusingly similar to a CBP recorded registered trademark, and restricted gray market articles (goods bearing genuine marks not intended for U.S. importation for which CBP granted gray market protection) are subject to detention and seizure.
However, travelers arriving in the United States may be permitted an exemption and allowed to import one article of each type, which must accompany the person, bearing a counterfeit, confusingly similar or restricted gray market trademark, provided that the article is for personal use and is not for sale.
This exemption may be granted not more than once every 30 days. The arriving passenger may retain one article of each type accompanying the person. For example, an arriving person who has three purses, whether each bears a different infringing trademark, or whether all three bear the same infringing trademark, is permitted only one purse. If the article imported under the personal exemption provision is sold within one year after the date of importation, the article or its value is subject to forfeiture.
In regard to copyright infringement, articles that are determined by CBP to be clearly piratical of a protected copyright, i.e., unauthorized articles that are substantially similar to a material protected by a copyright, are subject to seizure. A personal use exemption for articles, similar to that described above also applies to copyrighted articles for the personal, non-commercial use of the importer and are not for sale or distribution.
You may bring back genuine trademarked and copyrighted articles (subject to duties). Products subject to copyright protection most commonly imported include software on CD-ROMs, sound recordings, toys, stuffed animals, clothing with cartoon characters, videotapes, DVDs, music CDs and books. Products subject to trademark protection most commonly imported include handbags and accessories, and clothing.
And a side note to some people trying to mislabel things, the word they use is infringement.