The case against the IRS for targeting conservatives isn’t over after all. On Tuesday a federal judge in Ohio certified a class-action lawsuit against the IRS by conservative groups whose applications for tax-exempt status were slow-rolled between 2010 and 2013.

The lawsuit by the NorCal Tea Party Patriots was filed in May 2013, shortly after the targeting came to light. It will represent more than 200 groups. In July 2014 Judge Susan Dlott dismissed parts of the lawsuit but allowed key portions to go forward. Those include...