“Card check” is a method for employees to become represented by a labor union. Generally, card check requires the employer’s consent. If a majority of employees in a bargaining unit sign authorization forms, or "cards," stating they wish to be represented by the union and the employer agrees, a check of the cards by an independent third party can result in bargaining representative status for the union. Since the National Labor Relations Act (NLRA) became law in 1935, card check has been an alternative to the National Labor Relations Board's (NLRB) election process. Although a successful NLRB election also requires more than 50% support, a petition for an NLRB election only requires 30% support. There, the NLRB conducts a secret ballot election after authorization cards are submitted, and the Board determines that the union has made a “showing of interest” (i.e., 30% support). In both cases, the employer never sees the authorization cards or any information that would disclose how individual employees voted.” https://en.wikipedia.org/wiki/Card_check And per the Teamsters, it’s: “Procedure whereby signed authorization cards are checked against a list of employees in a prospective bargaining unit to determine if the union has majority status. The employer may recognize the union on the basis of this card check without the necessity of a formal election. Often conducted by an outside party, e.g., a respected member of the community.” https://teamster.org/member-resources/definitions-common-labor-terms/#c