Zuma's speech on justice ironic: Zille

President Jacob Zuma's remarks on the judiciary were ironic because it is under threat from interference by government, not the other way around, Democratic Alliance leader Helen Zille says.

"The irony of his presence at an 'Access to Justice' conference was trumped only by what he said, presumably with a straight face," Zille wrote in her weekly newsletter SA Today.

"He supported the separation of powers that lies at the heart of any democratic constitution. He then asserted that the independence of judiciary was adequately protected by the Constitution, but argued that the executive was not sufficiently protected from interference by the judiciary!" she said of Zuma's keynote speech at the third annual Access to Justice conference.

"In arguing that the courts could not supersede the voters' political mandate he missed the point that no matter how powerful a ruling party is, it cannot do what it likes. "It must abide by the Constitution. A popular mandate does not place a governing party above the law," Zille said.

"The threat to our criminal justice system is not the judiciary's interference in the executive. It is the other way around."

In his speech, Zuma warned the judiciary to stay out of politics.

"The executive, as elected officials, have the sole discretion to decide policies for government," the president said.

"This means that once government has decided on appropriate policies, the judiciary cannot, when striking down legislation or parts thereof on the basis of illegality, raise that as an opportunity to change the policies," he said.

Constitutional law experts have expressed concern at the president's remarks, saying the court had a right and duty to strike down legislation or policies that contradicted the principles of the Constitution.