The execution in Iran of 22-year-old Delara Darabi is more than a personal tragedy. It highlights the appalling inadequacies of Iran's justice system and its shocking treatment of young offenders in particular.

It is harrowing to learn of a woman, convicted under dubious circumstances, being forced to observe her own scaffold from her cell. It is still more to read the words she composed for an exhibition of her art, in which, "from behind the walls", she said "hello to the world".

That aside, from a judicial point of view, she was executed having been convicted of murder as a minor. Darabi was only 17 when she admitted killing her father's cousin, later to retract her confession. She was also hanged after Iran's chief justice ordered a stay of execution. That is possibly the most disturbing element, for it reminds us that power in the Islamic Republic is confusingly dispersed, often between secular and religious authorities.

Once again, those in charge of the agenda in Iran have shown their hard face towards the world, displaying contempt for the rights groups that pleaded for a re-examination of the case.

Iran is not the only developing country routinely to execute prisoners for capital crimes. But according to several rights groups, it executes more minors than any other – eight last year alone – breaking the UN Convention on the Rights of the Child, which it signed. Rights groups also say Iran keeps many youngsters on death row till adulthood before hanging them – to keep down the number of executed juveniles.

There is no direct link to be drawn between this execution and the recent anti-Western acts of Iranian leaders, including their cold response to the olive branch offered by Barack Obama, their continued enthusiasm for their nuclear programme and President Ahmedinejad's tirade at the UN anti-racism conference.

But what they all suggest is that hard-line conservatives remain in the driving seat in Iran, unaffected by America's attempts to engage. Depressingly, it seems that powerful elements in Iran do not want engagement. Darabi was one more victim of a mindset that remains closed to dialogue and shows no sign of changing.