Nobel economist Joseph Stiglitz said U.S. tax law that allows Apple Inc. to hold a large amount of cash abroad is “obviously deficient” and called the company’s attribution of significant earnings to a comparatively small overseas unit a “fraud.”

“Our current tax system encourages companies to keep their money abroad, opens up a vast loophole through what is called the transfer-pricing system that allows them not only to keep their money abroad but, effectively, to escape taxation,” Stiglitz, who advises Hillary Clinton’s presidential campaign, said in a Bloomberg Television interview with Tom Keene.

Stiglitz was speaking in response to a question about whether policy makers like Clinton and Senator Elizabeth Warren, a Democrat from Massachusetts, could develop a plan to encourage companies like Apple to bring their accumulated foreign earnings back to the U.S. Under current law, companies can defer U.S. income tax on their foreign earnings until they repatriate them, or return them to the U.S.

About $215 billion of Apple’s total $232 billion in cash is held outside of the country, third-quarter earnings results showed this week.

Apple is making use of existing gaps in the U.S. tax system to shift its U.S. taxable earnings overseas to low-tax Ireland. Proposed U.S. Treasury regulations are aimed at curbing so-called earnings stripping, and European tax regulators are examining the company’s tax practices.