The act was designed to curtail some of the powers unions had acquired under the wagner act.

My  Taft-Hartley Act of 1947

Why?: " The act was designed to curtail the powers unions appeared to have acquired under the Wagner Act. bars unions from unfair labor practices, makes collective bargaining agreements enforceable in district courts, and provides civil damages remedies to those injured by prohibited union activities." 

Hope I helped! :D

Taft-Hartley Act of 1947 designed curtail the powere unions appeared to have acquired the Wanger Act