Before IG Metall can call a strike, the members vote in an Urabstimmung, a ballot of the members. At least 75 percent of the members covered by the bargaining round must vote for the strike, in a secret ballot. The union’s executive board decides on the ballot at the request of the bargaining committee.
After a strike, the negotiated result goes to the members in a second ballot. This time, 25 percent yes is enough to accept it. With their vote, the members also declare that they agree with the result. The civil service federation dbb has similar thresholds, counted among those who vote.