InterDigital received a blow in its ongoing patent infringement case. The U.S. International Trade Commission’s (ITC) staff recommended in favor of South Korea’s Samsung Electronics, sending InterDigital’s shares down as much as 28%.

The U.S. ITC staff reportedly said that Samsung did not engage in unfair trade practices related to 3G mobile technology. However, Interdigital insists that Samsung infringed on five of its patents.

Last week, InterDigital and Nokia agreed to drop patent cases against each other.