Perceptions are key in the matter of who carries out inquiries into historic child abuse allegations.

Two religious orders are arguing that the woman appointed to lead the Scottish Government's inquiry might appear to be biased.

This is on the grounds that Susan O'Brien QC has previously acted in cases against the catholic order the Sisters of Nazareth. She helped alleged victims of abuse challenge a time bar which prevented them from bringing cases against the Catholic order over incidents of abuse they claim happened in its children's homes in the 1960s and 1970s.

On the face of it, Mr Duncan's clients have a case. But only if you have no faith in judicial independence. There is little doubt Ms O'Brien would defend her ability to hear any claims impartially.

In addressing an issue which has played out over a decade there will always be a balance to be struck between appointing someone with sufficient knowledge and experience and someone who has had no past involvement at all.

In fairness, similar arguments were advanced by victims and alleged victims of abuse in England in objecting to Susan Woolf QC, the choice of home secretary Theresa May to lead a similar inquiry.

The perception there was that she would be biased, due to connections with former home secretary Leon Brittan - who some suspect of covering up abuse claims.

The organisations seeking the judicial review, the Sisters of Nazareth an the Daughters of Charity of St Vincent de Paul have a duty of care to their staff and former staff and will want to guard their own reputations against any false claims.

But there is another perception that the two orders seeking to oppose Ms O'Brien's appointment would do well to take heed of.

The Catholic Church as a whole has been slow to respond to allegations of abuse and quick to cover up. The church and its orders needs to demonstrate that it was sincere in more recent pledges and pronouncements about facing up to what may have been done in its name in the past - rather than delaying answers for the many genuine victims of child abuse who have campaigned for years to have an inquiry. Many victims and survivors are now elderly or in poor health.

The selection of an appropriate chair for England's inquiry became a marathon process and it is important that the process of setting up Scotland's inquiry does not become similarly drawn out.

The Sisters of Nazareth and the Daughters of Charity will have their judicial review heard, but should have faith in the justice system to treat their people fairly.

It does not become the justice system to appear to be in the pockets either of those claiming to have been abused, or those defending claims. In England, there were eventually concerns that victims were dictating to the inquiry who could and couldn't lead it.

The court will make its decision on the judicial review, but it is to be hoped that it will do so quickly.

If the court does not back the Scottish Government's appointment a new chair must be identified quickly

But he or she must be chosen by ministers, and should not be subject to veto by either alleged abuse victims, or alleged perpetrators.