What is a showing of interest and when is it required?

A showing of interest means any of the following:  evidence of membership in a labor organization; employees' signed and dated authorization cards or petitions authorizing a labor organization to represent them for purposes of exclusive recognition; allotment of dues forms executed by an employee and the labor organization's authorized official; current dues records; an existing or recently expired agreement; current exclusive recognition or certification; employees' signed and dated petitions or cards indicating that they no longer desire to be represented by the currently recognized or certified labor organization; or cards indicating a desire that an election be held on a proposed consolidation of units; or other evidence approved by the Authority.  Section 2421.16.

The requirement that a showing of interest be made serves an administrative purpose to help avoid unnecessary expenditure of time and funds where there is no reasonable assurance that a genuine representation issue exists.