EIS ready to take on Catholic staff veto
But the practice of some schools of rejecting applications from non-Catholics for key posts could be at risk. The Educational Institute of Scotland is poised to raise a test case if a member is prepared to make a specific complaint. The union has taken legal soundings and believes it can win in the Court of Session.
Delegates to the institute's national conference have already taken exception to what they say is an unfair advantage for Catholic teachers who are free to choose between denominational and non-denominational secondaries.
Ms Marsh has been involved in a string of sex discrimination and equal pay cases involving Scottish local authorities over the past decade and speculates that non-Catholics may be able to claim religious discrimination under recent European legislation if they are excluded from certain posts.
John Oates, field officer for the Catholic Education Commission, said practice differed around the country depending on teacher supply but all posts in Catholic schools were still subject to "approval", and this was enshrined by law.
In an unrelated case, education officials recently warned that non-Catholic pupils hoping to gain entry to the popular Aberden Grammar - where places are held back for Catholics - could also claim religious discrimination under human rights legislation. This would be a reverse of the generally accepted right of Catholics to separate education.
But Ms Marsh predicted West Lothian would safely withstand a challenge in the Court of Session from a non-Catholic parent whose son was refused entry to the flagship St Margaret's Academy in Livingston.
Ms Marsh said: "The critical question is not whether there is discrimination, because obviously there is, but whether such a discriminatory effect meets the test of objective justification. If it does, the Human Rights Convention permits the discrimination. It is important to realise that a discriminatory effect per se will not be struck down: it will only be struck down if it is not objectively justifiable."
She added: "Insofar as a local authority attempts to preserve the religious character of a school, and produces admission arrangements aimed at securing that end, there is little in the case law of the European Court of Human Rights to suggest that West Lothian will not be able to avail itself of the objective justification defence.
"The convention can equally be invoked to protect the right of Roman Catholics to receive education in a denominational school, as enshrined in domestic law."
Ms Marsh predicts the recent legislation will lead to a series of "creative and imaginative challenges".
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