Alistair Carmichael: The difference between justice and revenge can’t be ignored

That led to a visit to death row, which led to a casual interest becoming a compelling political passion.

We can never allow ourselves to underplay the pain experienced by the victims of violent crime and their relatives.

To be clear, the overwhelming majority of those on death row are guilty of the crimes of which they were convicted.

Our legal system, however, has always been clear that justice and vengeance are different things.

There is little evidence of any deterrent effect from using the death penalty. Many of those jurisdictions that use it are among the most violent in the world. When balanced against the risk of miscarriages of justice that can never be reversed it becomes a no-brainer.

The use of the death penalty is not just inhumane to those on death row but is also dehumanising to the communities that use it.

The UK government’s position on this issue is clear and fixed.

We oppose the use of the death penalty in all circumstances and the UK continues to lead on this issue internationally.

Lord MacDonald, the former Director of Public Prosecutions, now a Liberal Democrat peer, travelled to California recently with the support of the government and NGOs to campaign for a yes vote in the referendum on the death penalty that the state will hold in November.

At home, earlier this year Vince Cable banned the export of drugs used in executions overseas.

This follows similar action in 2010.

As we mark the ninth World Day Against the Death Penalty, recent events in Gambia and elsewhere show that the need for action is as urgent as ever.

If opponents of capital punishment work together and make our voices heard then we can make a real difference.

We not only can – we must.

• Alistair Carmichael MP, is Deputy Leader of the Scottish Liberal Democrats.