The Western Cape High Court is set to hear an application by the Southern Africa Litigation Centre (SALC) which is seeking an order to set aside a visa granted to a convicted Dutch arms dealer.
Augustinus Petrus Kouwenhoven, 75, is wanted in the Netherlands, where he faces a 19-year jail sentence for crimes against humanity and for selling firearms to former Liberian president Charles Taylor.
He was granted temporary residency in South Africa in 2017.
The application was not being opposed by the Home Affairs minister and director-general, who were both cited as respondents alongside Kouwenhoven.
The SALC said Kouwenhoven was opposing its application and had even filed a counter application.
"Kouwenhoven argues that Form 29 of the Immigration Regulations is unconstitutional as it forces the Department of Home Affairs to deport an undocumented foreign national to their country of origin, instead of giving them an opportunity to be deported to a country of their choice," the SALC said in a statement.
The rights group will, however, argue that Kouwenhoven did not disclose his conviction for war crimes when applying for a visa.