Recent crackdowns on the opposition in Zimbabwe and Tanzania do not bode well for the region.

The Southern African Development Community (SADC) is supposed to advance democracy and human rights in its 16 member states. But its annual summit, which took place in Harare on Saturday, 17 August, is likely to be seen as advancing political repression instead.

Certainly in Zimbabwe, at least, where the ruling Zanu-PF has forcefully cracked down on its political opponents over the past few weeks, arresting, detaining and, in some cases, allegedly torturing about 165 of them, precisely out of fear that they would embarrass President Emmerson Mnangagwa by demonstrating against him at the summit.

Opposition stalwart David Coltart, the mayor of Bulawayo, called the crackdown "preventative detention", predicting the oppositionists would be released after the summit. Preventative detention is clearly also what happened in another SADC member state, Tanzania, last week.

The ruling Chama Cha Mapinduzi party suppressed opposition demonstrations, and hundreds of members of the main opposition Chadema party were detained to prevent them from holding a rally in Mbeya to celebrate International Youth Day on Monday, 12 August. They were released a day later.

Democracy and respect for human rights are enshrined in the SADC Treaty. But it was unlikely that the summit leaders would embarrass Mnangagwa, in...