Europe Settles Some Tax Scores

Finally, glimmers of a new old way to account for tax cuts and growth.

Americans are used to debating the impact of tax policy on economic growth, so it might come as a surprise (or not) that the European Union is far behind the curve in this regard. New research helping Brussels fill that gap is a breath of fresh air.

At issue is dynamic scoring, a method economists use to estimate how tax-policy changes affect economic growth, employment and revenue. Dynamic-scoring projections have featured prominently in U.S. debates for years. Yet EU economists cling to static scoring, a less realistic method...