Applications for asylum to the UK should be rigorously tested and scrutinised but the process by which this is done should be open, fair and subject to scrutiny itself.

What yesterday's judgment of the Supreme Court in the case of two immigrants who made applications for asylum in Scotland appears to demonstrate is that the use of language experts to test the credibility of claims is flawed and has the potential to lead to genuine asylum seekers being refused entry to the UK and being sent back to a country where they may face persecution.

The central issue in the case before the Supreme Court was the use of language experts provided by the Swedish company Sprakab to assess whether an applicant really is from the country they say they are from. The experts usually listen to a recording of the applicant speaking and, in this case, were asked to determine whether the asylum seekers were from a part of Somalia where they said they would be at risk of persecution. In both cases, the experts decided the applicants' speech was from Kenya rather than Somalia and the Home Office rejected their claims of asylum on that basis.

The use of such reports has already caused controversy in a number of countries in which Sprakab work but, last year, the Court of Session also ruled the UK Government's use of Sprakab experts was unlawful because they failed to demonstrate sufficient expertise and the experts also went beyond their remit. Now the Supreme Court has upheld that decision in a ruling that raises profound questions about the continued use of the language experts.

The first question is over the experts themselves. Sprakab insists its staff have detailed knowledge of the appropriate languages and countries but the Supreme Court said the expertise had not been demonstrated. In one of the reports, for example, the asylum seeker was said to be speaking a form of Somali spoken only in Kenya, even though there was no indication that the Sprakab expert had ever been to Kenya or studied the language there. The staff must have the appropriate expertise and to be seen to have it.

The second question centres on how much reliance is put on the expert's reports. In principle, there is nothing wrong with the Home Office using such reports but it appears that a negative report from Sprakab can more or less be the final word on the matter rather than one element among many pieces of evidence. Refugees' cases should be determined on the basis of all the evidence.

There are many other questions that need answered: what qualifications do the experts have? How widespread is their use? And what guidelines, if any, do they work to? In particular, the experts should not express opinions that go beyond the proper role of a witness. There is also an important issue of fairness: the Government should test asylum claims but the concern is that the use of language experts is part of a so-called culture of disbelief in which the Home Office seeks to demolish cases rather than assess them fairly (although Sprakab does support applicants more than it rejects them).

The hope is that the Home Office will use the Supreme Court's ruling as an opportunity to consider when and how the language reports should be used. Asylum seekers' cases must be scrutinised and checked but they also deserve to be evaluated not on the basis of a single report but on all the evidence, assessed openly and fairly.