Give Chris Grayling some credit: he has listened to objections over his judicial review proposals and tried to respond. It’s just he got his response wrong.

The lord chancellor and justice secretary could hardly have ignored the protests: the legal profession, House of Lords and even a handful of his own MPs (though few, alas, from the Liberal Democrats) have made their feelings perfectly clear.

They told him that preventing judges from granting permission for judicial review when a public body has acted unlawfully was fundamentally wrong. Grayling has stated that when an outcome would have been the same regardless of an unlawfulness challenged, JR is  a costly and fruitless experience.

The lord chancellor has been impervious to any argument on this point: he ignores that this change gives judges an almost impossible task of ruling on the outcome of a JR even before granting permission. Grayling’s casual approach to public authorities acting unlawfully also jars with his official role as an upholder of the rule of law.

But last night the lord chancellor dangled an olive branch in the form of judicial discretion. Judges would, he offered, have flexibility to be able to grant permission in cases meeting an ‘exceptional public interest’ threshold.

Was this the moment campaigners were waiting for? Hardly. But more damagingly for Grayling, this clause seemed to stir lawyers on his own side into rebellion.

Former solicitor general Edward Garnier called the wording ‘moderately nonsensical’ and asked him to think again. Former attorney general Dominic Grieve, who David Cameron must increasingly wish had been kept in the cabinet rather than shunted out to speak freely, described the new clause as ‘restrictive’.

The main problem seems to be that no-one can understand what ‘exceptional public interest’ means. Grayling dismissed naysayers, telling the few MPs who bothered to turn up for the debate that ‘these are straightforward terms in the English language, and we are simply setting the bar one step higher than public interest’.

He went on: ‘It seems to me to be a simple proposition to say that a court must certify that a matter is of exceptional public interest—which might relate to a major, fundamental and worrying breach of procedure by a public body—rather than of general public interest.’

The legal minds sitting behind him clearly didn’t agree this was so simple.

Who is to define what ‘exceptional’ means? Is there an exceptional public interest in the legal aid system? In parcels received by prisoners? Even in the burial place of Richard III, so often the go-to case for Grayling as he cites the kind of spurious JR he wants to restrict? All have some form of public interest – who is Grayling to say that one is more exceptional than another?

The only certainty is that the courts will have to do the legwork – and foot the bill – for the satellite litigation that is likely to follow.

Grayling wanted a concession to make this all go away. Instead he’s likely to have opened a new can of worms.