(a) Upon receipt of the petition in the Regional Office, it is filed, docketed, and assigned to a member of the staff, usually a field examiner, for investigation. The field examiner conducts an investigation to ascertain:

1. (1) Whether the employer's operations affect commerce within the meaning of the Act,
2. (2) Whether there is in effect an agreement requiring as a condition of employment membership in a labor organization,
3. (3) Whether the petitioner has been authorized by at least 30 percent of the employees to file such a petition, and

4. (4) Whether an election would effectuate the policies of the Act by providing for a free expression of choice by the employees.

   The evidence of designation submitted by the petitioner, usually in the form of cards signed by individual employees authorizing the filing of such a petition, is checked to determine the proportion of employees who desire rescission.