By Catherine Stihler, Labour MEP for Scotland and former rector of St Andrews University

At the turn of the century, EU member states came together in a spirit of solidarity to harmonise extradition rules.

The intention was that the European Arrest Warrant (EAW) would be used if there was a significant risk to the public, such as in terror-related cases.

It was used, for example, to allow the extradition of one of the suspects in the 2005 London bombings from Italy.

What it was not intended for was its use by a member state to target political opponents.

That is what I believe the Spanish Government is now doing with the issuing of five EAWs against senior figures of the previous Catalan Government.

One of the people targeted is Clara Ponsati, currently a professor at St Andrews University.

There has been an outcry against the Spanish Government, and much of the criticism in Scotland has come from SNP figures. For many in the Scottish nationalist movement, it is about demonstrating support for the Catalan independence campaign.

I firmly oppose Scottish independence and I campaigned to keep the United Kingdom together, just like I campaigned to keep the EU together, because I passionately believe we achieve more when we work collectively.

We had a legally-binding referendum on independence in Scotland, approved by both governments, and the SNP lost by a significant margin.

All people have the right to self-determination and that is why I campaigned for devolution and the creation of the Scottish Parliament. Despite my strong opposition to Scottish independence, I believe the Spanish authorities have made a terrible misjudgement.

Arrest warrants should not be used to settle domestic political disputes in this way.

Should these five people in question be sent back to Spain, which is likely to happen at some point, how can we be confident that their fundamental rights will be protected and that they have a fair and open trial?

I want the European Commission to intervene to ensure their human rights are respected, and I want EC president Jean-Claude Juncker to make urgent representations on behalf of member states.

We cannot simply have one of our own members suppressing and quashing political divergences within its own state.

Around the world, other countries have attempted to quash political movements asking for change. How can the EU remain critical of such tactics if it remains silent about Spain?

This should not be an issue that is linked to support or opposition to Scottish independence. This is matter of natural justice that should unite everyone in Scotland, the UK, and across Europe.