Republicans talk often about using the “power of the purse” to rein in a lawless Obama administration. If they mean it, they ought to use their year-end spending bill to stop a textbook case of outrageous executive overreach.

This scandal comes courtesy of the Justice Department, which for 16 months has engaged in a scheme to undermine Congress’s spending authority by independently transferring dollars to President Obama’s political allies. The department is in the process of funneling more than half-a-billion dollars to liberal...