The Times Editorial: Yesterday's ruling declaring invalid the appointment of Menzi Simelane as national director of public prosecutions is deeply embarrassing for President Jacob Zuma.

The Supreme Court of Appeal judgment - just two days after Zuma was castigated for appointing a close ally to head the Special Investigating Unit - flays the president over Simelane's appointment, saying it was "inconsistent with the constitution" if read with the National Prosecuting Authority Act.

It is Zuma's prerogative to appoint allies and trusted comrades to be his spokesmen, or his advisers, or his ministers, but in a constitutional democracy such as ours he simply cannot play fast and loose with state institutions whose independence is underpinned by the supreme law of the land.

The National Prosecuting Authority is one of those institutions.

Handing down the judgment yesterday, Judge Mohammed Navsa said the president could not, on the available evidence, have reached a conclusion favourable to Simelane as there were "too many questions concerning his integrity and experience".

Simelane's reputation took a battering during the 2008 Ginwala inquiry, which found that the then director-general of the Department of Justice had given evidence that ''left much to be desired''.

Yet Zuma, on the advice of Justice Minister Jeff Radebe, proceeded to appoint Simelane to the crucial position of national director of prosecutions barely a year later.

Simelane was just 38 at the time and had practised as an advocate for two years.

Yesterday's ruling will be reviewed by the Constitutional Court, but Zuma and Radebe would do well to reflect on the appeal court's finding that they made material errors in fact and law, and that the appointment was in breach of the constitution.

Let us hope the ruling party resists the temptation to use it to launch another broadside against the courts.