U.S. Sen. Bernie Sanders says it¡¯s worth following the example of ¡°our brothers and sisters in Iceland¡± who last year passed the world¡¯s most demanding law on equal pay for men and women. But the legislation, which took effect on Jan. 1, could end up hurting women without some added measures. Even ultra-egalitarian Iceland isn¡¯t ready to take them.

No other country has gone as far as Iceland in demanding equal pay for equal work. The 2017 law doesn¡¯t just expose a company that violates the principle to lawsuits. It requires all firms with 25 or more employees to set a value for each task a worker in a certain position is expected to perform, then fix salaries to the sum of those values. Bigger companies have a year to certify their compliance, obtained from authorized assessors, to the country¡¯s government Center for Gender Equality. The smallest ones have until the end of 2021. Recertification is due every three years, the law stipulates.

Iceland is doing this to redress a pay gap of 5.7 percent (although women¡¯s rights activists use higher numbers). Only one rich nation ¡ª New Zealand ¡ª has a slightly smaller gap; it¡¯s 18 percent in the United States. The payroll certification will probably shrink it further, making Iceland the undisputed world leader in this area. But it will likely hurt women¡¯s labor market participation there.