Some corporations have sought to learn of union activities by employing informants, the same way that unions employ salts to infiltrate a non union organization to gather propaganda and sow discord to gain union support. A "plant" or salt can be used to disrupt meetings, question the legitimacy and motives of either the union or management, and report the results of the meetings to their superiors. Disruption or reporting on union meetings is illegal, but can be difficult to prove in ULP hearings.