The purpose of the picket is to peacefully encourage non-striking employees and members of the public to oppose a lock-out or to support strikers involved in a protected strike. The nature of that support can vary. It may be to encourage employees not to work during the strike or lock-out. It may be to dissuade replacement labour from working. It may also be to persuade members of the public or other employers and their employees not to do business with the employer.
The strike must be a protected strike. In normal cases, employees picket at their own place of work in support of their strike against their own employer. Cases do arise, however, where employees picket at their own place of work in support of a strike between another employer and its employees. This is what is contemplated in section 66 as a "secondary strike". In this case, in order to be protected, the picket must further satisfy the requirements of a lawful secondary strike in terms of section 66 of the Act. This is because the definition of "secondary strike" in section 66 includes "conduct in contemplation or furtherance of a strike: A picket is "conduct in contemplation or furtherance of a strike".
The requirements for a protected secondary strike are:
The strike that is to be supported by the secondary strike must itself be a protected strike;
the employer of the employees taking part in the secondary strike must have received written notice of the proposed picket at least seven days prior to its commencement; and
If a picket is in support of an unprotected strike, the picket is not protected by section 69 of the Act.
Pickets may be held in opposition to a lock-out . Section 69(1) does not distinguish between protected and unprotected lock-outs. This means that a picket may be authorised and held in opposition to a protected or an unprotected lock-out.