The Cape High Court has given Police Minister Nathi Mthethwa 90 days to draw up guidelines for compensation for firearms surrendered under the gun control law.
The ruling could result in pay-outs totalling millions of rands for gun owners who have handed in weapons since 2004.
The order was handed down on Monday by Acting Judge President Jeanette Traverso, who at the same time slapped down an attempt by Mthethwa to distance himself from the bungling of his predecessor.
It followed an application by the Justice Alliance of SA (Jasa) and the False Bay Gun Club.
They argued that the Firearms Control Act, which came into force in 2004, required the minister to come up with guidelines on the amount of compensation to be paid for guns surrendered or forfeited to the state.
By failing to do so, Mthethwa and his predecessor Charles Nqakula had acted in breach of the "ethos of accountability" in the constitution.
Though the two sides agreed before Monday's hearing on a draft order of just three clauses, Mthethwa apparently developed a change of heart at the last minute.
When the matter came before Judge Traverso, advocate Kosie Olivier said Mthethwa, his client, would not oppose clauses ordering him to draw up the guidelines within 90 days, and to pay the applicants' costs.
However, Olivier told the judge the minister did oppose the inclusion of the first clause, a "declarator" that the failure to establish the guidelines was unlawful and unconstitutional.
Olivier asked that the matter be postponed so more affidavits could be filed to explain Mthethwa's involvement.
"But why?" demanded an incredulous Judge Traverso.
Olivier said his instructions were that Mthethwa took office only after the April, 2009, elections, and had been unaware of the guidelines issue.
"So what?" demanded the judge.
"This is not a personal application against someone, it's ex officio... Argue the law to me, don't tell me about your instructions."
She said that in his written heads of argument, Olivier had in fact conceded that the failure to draw up guidelines was unconstitutional.
Jasa's lead advocate, Peter Hodes, said Mthethwa was seeking to absolve himself from blame.
"He wants to give what is in rugby parlance called a hospital pass to the previous minister," he said.
Judge Traverso refused the postponement, and made the full order.
Jasa spokesman John Smyth said the ruling would lead to the pay-out of what could total millions of rands to gun owners.
"The order says what has gone on for the last five years is unlawful and unconstitutional," he said.
"The state has received a very robust slap on the wrist from her ladyship."
Jasa would now wait for the guidelines to be issued.
If they were not satisfactory, this would not be the end of the matter, he said.
If they were unchallenged, firearms control officers would have to deal with a huge compensation backlog.
In 2005, Nqakula told Parliament no compensation would be paid to gun owners who handed in their weapons.
The same year, then-national police commissioner Jackie Selebi told MPs there was no budget for compensation, and "you can't be paid for doing away with an evil thing".