Decius wrote:

Tehran's Revolutionary Court sentenced 11 people to death after convicting them of participating in post-election riots, state media reported Thursday.

Two of the sentences have been carried out; the rest are under appeal, the Iranian Students News Agency said, quoting a court official.

If your purpose is to scare people, is there political utility in the perception that trials are unfair and results arbitrary and severe?

yes -- see Stalin see Hitler see Robespierre - showtrials and execution
fear is a potent political weapon with a great deal of political utility - all that is required is ruthlessness and it is a path once ventured down from which there is no retreat (see Robespierre - I think he tried to balance genuine ethics and political violence and it tore him apart as a human being and destroyed the revolution [I recommend the movie Danton]).