On Thursday, the nonpartisan Congressional Research Service republished an analysis that found no clear relationship between marginal high-end tax cuts and economic growth.
The new version (PDF) stands by the larger conclusion:
This analysis finds no conclusive evidence, however, to substantiate a clear relationship between the 65-year reduction in the top statutory tax rates and economic growth. Analysis of such data conducted for this report suggests the reduction in the top tax rates has had little association with saving, investment, or productivity growth. It is reasonable to assume that a tax rate change limited to a small group of taxpayers at the top of the income distribution would have a negligible effect on economic growth.