One federal statute, the Tucker Act, provides a 6-year statute of limitations to sue the government for claims "founded . . . Upon the Constitution." Another statute, the Internal Revenue Code, requires that claims for refund of tax overpayments be filed within 3 years of filing the relevant tax return. The Supreme Court decided 4/15/08 that the longer Tucker Act statute of limitations may not be used for a claim for the recovery of taxes assessed in violation of the Export Clause of the Constitution.
The taxes had been imposed on coal mined in the United States, but those taxes were later found to be unconstitutional. The taxpayers sued the government and won both their back taxes and interest in the lower courts. The Supreme Court found the tax refund statute to be clear on its face, and saw no reason to give taxes imposed in violation of the Export Clause any different treatment from taxes challenged on some other grounds.