Twice in the last four months, the U.S. Supreme Court has declined to hear appeals of lower court rulings regarding the Harbor Maintenance Tax (HMT). For exporters, that's both good news and bad news.

In 1998, the Supreme Court ruled that the HMT, a value-based charge on goods shipped by water, was unconstitutional when applied to exports. That led to a series of lawsuits regarding refunds. Among the questions that exporters have asked the courts to decide are how far back they may file claims for refunds, what documentation is required to obtain a refund, and whether the federal government must pay interest on refunds.

In December, the high court declined to hear the government's appeal of United States v. Swisher. That let stand a lower court ruling that exporters that followed certain claim-filing procedures with the U.S. Customs Service would be eligible for HMT refunds dating back to 1987, the year the tax was first imposed.

That's the good news. The bad news is that in February, the Supreme Court declined to consider the plaintiff's appeal in IBM v. United States. That case centered on whether the federal government should pay interest on refund claims that were filed with the U.S. Court of International Trade. That court had said that the statute establishing the HMT allowed for interest on refunds, but the U.S. Court of Appeals for the Federal Circuit overruled that decision. By refusing to hear the case—partly because it involved statutory interpretation, not constitutional law—the high court let stand the appeals court's decision.

The subject of interest is not dead, however, says international trade attorney Matthew T. McGrath, managing partner of Barnes, Richardson & Colburn and aLogistics columnist. In March, IBM asked the trade court to consider whether interest would be due because the tax constituted an "unjust taking" of property for which "reasonable compensation," including interest, must be paid. Neither the trade court nor the appellate court ever considered that issue, says McGrath, and at least one other federal appellate court has ruled favorably on a similar claim. This time, the high court would be more likely to step in because it would involve constitutional interpretation.

Meanwhile, the U.S. Customs Service has issued refunds for payments made in the late 1990s. Customs, the courts, and exporters are working out a process for issuing refunds for earlier payments. Until now, exporters have had to submit copies of original HMT payment documents. But those records often are unavailable, in part because Customs requires companies to keep only five years' worth of records. What's likely to happen, McGrath says, is that Customs will provide exporters that have already initiated claims with computerized records of payments, which exporters must certify as accurate in order to receive refunds.