What is the test for awarding attorneys' fees and expenses to the prevailing party?

28 U.S.C. 2412(d)(1)(A) mandates the award of attorneys' fees and expenses to the prevailing party unless the court finds that the position of the United States was substantially justified or that special circumstances make an award unjust. To prove substantial justification, the government must show that its position has a reasonable basis in law and fact. Pierce v. Underwood, 487 U.S. 552, 565, 108 S.Ct. 2541, 2550, 101 L.Ed.2d 490 (1988). The government has the burden of demonstrating substantial justification. Bay Area Peace Navy v. United States, 914 F.2d 1224, 1230 (9th Cir.1990).