Johannesburg — There was a glimmer of hope last week in the home of the Dubes, a black family from the South African township of Soweto. Son Abel Dube was told he would soon be released from jail where he had been held since April 1982. But on his release, Abel was given another type of sentence: He was banished to the far-northern town of Messina, 300 miles from his family in an area of white political ultraconservatism.
Abel Dube's case is noteworthy because he has apparently committed no crime. Yet he was kept behind bars for 21/2 years, making him one of the longest-serving prisoners under South Africa's ''preventive detention'' laws.
Now he has been sent to Messina for three years under a security law provision that greatly restricts his freedom but does not require any explanation from the government as to why the action was taken. He has been given a place to live and a job on a copper mine.
The punishment of Dube is one of the more extreme examples of how South Africa can deal with black political opponents by using certain security laws. Among other things, these laws allow for people to be held by police but never brought to court. One group opposed to these security laws, the Detainees' Parents Support Committee (DPSC), called the government's action against Dube ''vindictive in the extreme.''
South Africa's preventive detention statute allows the minister of law and order, Louis Le Grange, to incarcerate any person he feels ''engages in activities which endanger or are calculated to endanger the security of the state....'' Dube was never charged with any offense nor did he ever appear before a court.
In general, the South African government believes that detaining people not necessarily guilty of criminal conduct is essential to combating what it regards as ''terroristic and other subversive activities.''
Until a few months ago Dube was the only person behind bars under the preventive detention law. But recently the law has been used to try to halt black unrest by skimming off leaders of opposition organizations such as the United Democratic Front and the National Forum.
Apparently 11 people are now being held for ''preventive'' reasons and another 190 detained for security reasons unrelated to criminal activity. The total number of arrests so far this year of people never charged with a crime, including those held under ''preventive detention,'' is just over 1,000, says a DPSC spokesman.
The circumstances of Dube's arrest and his background remain something of a mystery. No firsthand account by Dube is possible. His banning order means he cannot express his views publicly in South Africa.