Instagram and other social media platforms have become fertile ground for all manner of intellectual property disputes. Copyrighted fashion designs are easily ripped off, counterfeits spring up around popular products, and hashtags can quickly go from fair-use identifiers to Lanham Act violations.

Use of hashtags is one of several advertising issues examined in a recent case in the Northern District of California. Plaintiff Align Technology, Inc., best known for its “Invisalign” product, sued Strauss Diamond Instruments, Inc. over advertisements Strauss posted on Facebook, LinkedIn, Instagram, and YouTube.

Align makes and sells the iTero Element scanner, which takes sophisticated intraoral dental scans. The iTero Element system includes a “wand,” and a protective sleeve for the portion of the wand that enters the patient’s mouth. Align holds various trademark registrations for iTero, iTero Element, and Invisalign. Strauss, meanwhile, makes the MagicSleeve, a silicone sleeve designed for use with the iTero Element. Strauss targets customers of Align’s iTero sleeves.

In the advertisements at issue, Strauss used the hashtags #invisalign, #itero, #iteroscanner, and #iteroelement with images of the MagicSleeve. Align moved for a preliminary injunction, and Strauss claimed the nominative fair use defense. The court found that the fair use defense failed, and that Align was likely to succeed on its trademark infringement and false association claims.

The court held that nominative fair use did not apply because Strauss used more of Align’s marks than was reasonably necessary, and in some cases, the hashtags were used to identify Strauss’s MagicSleeve, rather than iTero Element. The court assessed the use of Align’s protected marks in the context of all of the hashtags used on the ad to discern the total impact of the reference. The court found that the use of Align’s protected marks, alongside hashtags referencing MagicSleeve, Strauss, dentistry, and attractive teeth, were “collectively being used to promote and describe the MagicSleeve,” rather than to identify the products. The court went even further, finding that the hashtags did not perform an identification function at all, but only imparted an implied association.

While the case is in its early stages, this decision makes it clear that marketers must tread carefully when using protected marks in hashtags. Hashtags are undoubtedly a powerful tool, especially when used to target a competitor’s market, but can draw lawsuits if not used within the bounds of the Lanham Act.