"Members had felt frustrated because we had been engaging with the city for two years," SJC general secretary Phumeza Mlungwana testified.
"The decision was that we needed very strong action to get the mayor's attention."
Mlungwana and 20 other members were arrested in September last year after singing and dancing at the stairs of the Cape Town civic centre without giving the city notice. Some of them had chained themselves to the stair railings, forming a human chain.
They had wanted to speak to mayor Patricia de Lille about the frustration at the city's perceived inaction over proper sanitation in informal settlements like Khayelitsha.
They were charged with convening a gathering or alternatively, convening or attending a prohibited gathering.
The group pleaded not guilty on the basis that their actions were not criminal.
Their lawyer Michael Bishop had applied for them to be discharged on Thursday, but this was refused.
Mlungwana said the SJC had fought tirelessly since 2008 to promote rights envisaged in the Constitution, accountability and active citizenship.
They decided to focus on sanitation after receiving numerous complaints about a lack of maintenance and consultation.
The SJC had been excited when De Lille committed to a janitorial service for informal settlement toilets at a sanitation summit in 2011.
Mlungwana said the implementation failed because of a lack of policy. The city eventually started stalling and "playing hide and seek".
The SJC's executive council decided last year that they would go to the civic centre and not leave until they had handed over a letter of demands.
"We chose 15 people because we didn't want to apply for the picket and wanted to stay within the law," Mlungwana said.
She will resume her testimony on October 7.