The National Crime Agency is in trouble again.

Having faced strident criticism by the divisional court for failing - by a distance - to comply with its duty of candour when applying for a search warrant in Operation Heterodon, now the Investigatory Powers Tribunal (IPT) has waded in, as a result of the NCA’s conduct during the same investigation into money laundering which targeted, among others, a party of successful businessmen brothers.

A judgment handed down by the IPT on 20 July again highlighted the NCA’s failure to disclose relevant information - this time to the Surveillance Commissioner - and has prohibited the NCA from using material obtained in the course of its investigation.

It was during an early interim hearing in the judicial review proceedings (challenging the validity of the search warrants) that the NCA admitted for the first time that covert devices had been installed in the business premises, authorised by the Surveillance Commissioner under sections 93 and 97 of the Police Act 1997.

This led to a rare application to the IPT.

The main plank of the IPT complaint was, once again, that deliberate non-disclosure by the NCA of the ‘main objective’ of its plan was a material non-disclosure that fatally compromised the commissioner’s authorisation. That main objective was to provoke a ‘behavioural reaction’ from the brothers: they would be arrested, interviewed and then bailed.

It was hoped and expected that they would then discuss their alleged predicament in incriminating terms that would be captured by the covert devices.

The IPT concluded it should have been ‘starkly apparent’ to the NCA that such a behavioural reaction might include material subject to legal professional privilege (LPP) being recorded ‘…either because lawyers would attend [the premises] to discuss the position and advise all the complainants, or at least by virtue of telephone conversations in which, even if the answers of the lawyer were not audible, advice would be sought’.

When covert surveillance risks the acquisition of LPP material, the Regulation of Investigatory Powers Act (RIPA) covert surveillance code of practice states it should only be authorised in ‘exceptional and compelling’ circumstances. Given that the commissioner was kept in ignorance of the main objective, the existence of exceptional and compelling circumstances was not addressed.

Further, the code of practice further obliges the NCA either to take steps to mitigate the risk of acquiring LPP material, or to put in place steps to protect it. It did neither.

In defence of the shortcomings in the search warrant applications, the NCA relied upon the inexperience of the officer who drafted them. This approach was not open to it in front of the IPT; the application for authorisation was an ‘experienced officer’ who had ‘prepared probably 40 or 50 such applications’ over seven years. Nevertheless, the IPT was satisfied that the NCA ‘genuinely did not consider that there would be LPP (or did not turn their mind to it) in the material…’ .

Despite the above, and the NCA’s reluctance to disclose to the IPT its original, deficient, application to the commissioner, the IPT was as reluctant as the divisional court to make a finding of bad faith. However, the NCA is now prohibited from listening to, or otherwise using, the covert recordings unless any of the complainants are charged (by 31 March 2016 at the latest).

What will rightly concern any observer of this sorry tale is that the NCA’s conduct is characterised by a readiness to withhold crucial information from independent decision-makers, by ignorance of its statutory obligations and by - on the most generous interpretation - a naivety in respect of the likely consequences of its self-styled ‘lawfully audacious’ plan.

The brothers are fortunate enough to have the means to challenge such audacity (though despite their success, the IPT declined to award them compensation, damages or costs), but how many other similar situations go unexamined?

Edmund Smyth is a criminal defence solicitor at Kingsley Napley