Supply-side activists are rejoicing in the award of a Nobel Memorial Prize in Economics to Stanford’s Robert Hall, the author of the flat tax that would replace the existing tax system with a single flat rate.

“It surely adds credibility to the flat tax, that even those people would think it’s good,” Arthur Laffer, a longtime GOP adviser who is credited with helping develop supply-side economics in the 1970s, told the Washington Examiner on Monday after the announcement of the award.