Patentees tend to fare well in proceedings before the US International Trade Commission (USITC). Under Section 337 of the 1930 Tariff Act (as amended), patentees can file a complaint with the agency that alleges importation of infringing products. Unlike ordinary courts, the USITC is not authorized to award monetary damages. However, the agency can (and regularly does) issue injunctive relief in the form of exclusion orders enforced by US Customs and Border Control agents. A second hitch with USITC proceedings is that the US President is given the opportunity to reject any exclusion order issued by the USITC.
As part of the mobile patent wars, Samsung filed a Section 337 complaint against Apple alleging patent infringement. Although Apple is a US company, it still imports its products from China and is thus susceptible to USITC action. And, although the USITC's stated mission is to protect US domestic industry, foreign-based companies (such as Samsung) are still permitted to file complaints with the agency to protect their US intellectual property rights.
After a full process, the USITC determined that Apple's iPhone 4 infringes Samsung's US Patent No. 7,706,348 (claims 75, 76, 82, 83, 84). The USITC consequently issued an exclusion order. Now, however, the US Trade Representative (as official representative of the Obama Administration) has issued a letter of disapproval based upon the conclusion that Samsung's commitment to FRAND licensing of its patents. http://www.ustr.gov/sites/default/files/08032013%20Letter_1.PDF. The denial effectively ends Samsung's case at the USITC. However, Samsung has also asserted the patent in a parallel lawsuit in Federal Court (Delaware). That Delaware case has been stayed (with consent of both parties) pending outcome of the USITC case.