SANDU v Minister of Defence (1999)  South African National Defence Union v Minister of Defence & Another, an important case in South African labour law, concerned the question of whether or not it was constitutional to prohibit members of the armed forces from participating in public protest action, and from joining trade unions. Justice Hartzenburg, in the Transvaal High Court, declared that a provision of the Defence Act prohibiting members of the Defence Force from becoming members of a trade union, and from engaging in any “protest action” as defined in the Act, was unconstitutional. To have any force and effect, however, the declaration of invalidity had to be confirmed by the Constitutional Court. The Minister of Defence and the Chief of the Defence Force (the respondents in this matter), opposed confirmation of the order of invalidity only in respect of the prohibition on joining trade unions. The South African Defence Force Union (the applicant) accepted that strike action was inappropriate in the military context, but argued that this should not prevent members of the Defence Force from joining a trade union. In a majority judgement, delivered by Justice O'Regan, the Constitutional Court decided that prohibiting participation in acts of public protest violated the right to freedom of expression of Defence Force members. This curtailed the right of Defence Force members to receive and express opinions on a wide range of issues, whether in public or private gatherings, and amounted to a grave infringement on the fundamental rights of soldiers. The court determined that this infringement constituted an unjustifiable limitation upon the right to freedom of expression, and was consequently unconstitutional. The court indicated, however, that a different legislative provision, narrower in its scope, may be constitutionally justified. This question, though, was obviously not before the court. The applicant argued that prohibiting membership of a trade union infringed the constitutional right of “every worker” “to form and join a trade union.” Turning to international law, as mandated by the Constitution, O’Regan considered the Convention on Freedom of Association, which specifically provides that soldiers and spies may join trade unions, but does not prescribe the facets of trade-union life to which soldiers and spies are entitled. These questions are left to the country in question to regulate and determine itself. Referring to the International Labour Organization’s construction of “worker”, Justice O’Regan interpreted the term “every worker” to include members of the armed forces, even though their relationship with the Defence Force is unusual and not identical to that of an ordinary employment relationship.