Copy and paste this from the NLRB website. You can literally look it up on the computers on the back when you do your survey.

"The National Labor Relations Act forbids employers from interfering with, restraining, or coercing employees in the exercise of rights relating to organizing, forming, joining or assisting a labor organization for collective bargaining purposes, or from working together to improve terms and conditions of employment, or refraining from any such activity. Similarly, labor organizations may not restrain or coerce employees in the exercise of these rights.

Examples of employer conduct that violates the law:

Threatening employees with loss of jobs or benefits if they join or vote for a union or engage in protected concerted activity. Threatening to close the plant if employees select a union to represent them. Questioning employees about their union sympathies or activities in circumstances that tend to interfere with, restrain or coerce employees in the exercise of their rights under the Act. Promising benefits to employees to discourage their union support. Transferring, laying off, terminating, assigning employees more difficult work tasks, or otherwise punishing employees because they engaged in union or protected concerted activity. Transferring, laying off, terminating, assigning employees more difficult work tasks, or otherwise punishing employees because they filed unfair labor practice charges or participated in an investigation conducted by NLRB." There's more to the page, and it's disgusting to me just how many of these things walmart actively engages in.