AP Landman, acting for Joseph Koetle, Solly Shoke and William Mabele, told the Truth and Reconcialitio Commission amnesty committee his clients had revealed the true facts of what had happened on May 20, 1987.
Koetle was responsible for the actual planting and detonating of the car bomb, while Mabele, only 19 at the time, was used as a driver to get Koetle to and from the court building.
Solly Shoke was responsible for supplying the bomb material. The three were all members of Umkhonto we Sizwe (MK), the African National Congress' armed wing.
Four policemen - constables Weyers Botha, Christoffel Botha, Kobus Wilkens and Andre Duvenhage - were killed while three other policemen and 11 civilians were injured when the 100kg car bomb was detonated at the court building.
"They made full disclosures on the role they played in the incident," Landman told the committee.
He said there was also no doubt Koetle had acted under instructions of General Siphiwe Nyanda, who at the time was in command of MK in Transvaal. He was also the chairman of the Swaziland Regional Politico-Military Committee.
Nyanda was earlier this year appointed as the first black chief of the SA National Defence Force.
Koetle, now a senior SANDF officer, testified he had been briefed on the operation by Nyanda, who was in Swaziland at the time.
Koetle said Nyanda had masterminded the bombing.
Landman said Nyanda could give these orders without consulting higher structures. "He was very high up in the command structures of MK."
According to Landman, who represented Nyanda as an implicated person, the SANDF chief has confirmed that the order eminated from him.
Nyanda has applied for amnesty together with a number of other ANC members and he will appear before the commission at a later stage.
On Friday Landman submitted it was apparent from the evidence that the aim was not to attack buildings as such, but to select those avenues where police would be.
"It is also significant that an attempt was made to entice police to the scene, but at the same time to prevent civilian casualties."
Landman said the manner in which the operation was carried out indicated a conscious effort to minimize civilian casualties.
He said because of the intensification of the armed struggle at that stage, the ANC's policy of avoiding civilians being hurt could no longer be sustained. The injury of civilians in the explosion should be seen in this light.
Landman said the three applicants acted with the aim of furthering the objectives of the ANC and MK.
"Their aims clearly fell within the context of the armed struggle being moved into white areas and the fact that policemen were part of the government machinery and therefore legitimate targets."
Landman said while Mabele had not been a member of the ANC at the time of the bombing, he supported the objectives of the ANC.
Shoke earlier testified he had sent Mabele out of the country after the bombing. He later received training and became a member of MK.
One of the victims injured in the bombing, Captain Chris, Esterhuizen, and the mother of Constable Kobus Wilkens said they would not oppose the amnesty application.
They provisionally opposed the application in case the applicants did not make a full disclosure.
Leading evidence, TRC commissioner Paddy Prior said whether the committee decided to grant amnesty or not to the three applicants, it should take cognizance of the fact that four young policemen had died in the attack and several others were injured.
"We should also remember that civilians of all walks of life attended court proceedings at this court, Prior said.
Judgment on the application would be given at a later stage.
Meanwhile the hearings into the 1988 Ellis Park bombing in which two people died and 35 others injured, was also postponed to a later date because the legal counsel for Lester Dumakude, the MK cadre who planted the bomb, was attending another hearing.
The hearing was postponed earlier this week to give Eric van der Berg a chance to receive instructions from Dumakude on contradictions between his testimony and that of the other two applicants Harold Matshididi and Aggie Shoke.
Committee chairman Judge Andrew Wilson said the rest of the Ellis Park hearing would be combined with another of the commitee's hearings.
Hearings on applications of Dick Hlongwane for a bombing at the Ellis Park sports arena in 1987 and of Solly Shoke for a number of police station bombings in the Johannesburg area, will be heard at a later stage.