I was Tulisa’s defence lawyer during her trial with the Fake Sheikh – and I still think some journalists need to be stopped

The Tulisa sting produced 72 hours of recordings. It took hundreds of hours of listening to detect a whispered instruction to his assistant to take Tulisa to the toilets, off tape, and offer her £3.5m for acting the part of a drug dealer – something that Mahmood denied on oath but sound experts confirmed

Tulisa Contostavlos' trial collapsed earlier this year (PA)

The conviction of Mazher Mahmood – also known as the “Fake Sheikh” – for perverting the course of justice in the trial of Tulisa Contostavlos is a rare victory for the victims of this type of sting, and it reveals exactly how unfair the law is in this area. But it also shows how far we have to go.

Investigative journalism has a long and distinguished history in the UK. It has exposed scandals including MP’s expenses, phone hacking, sexual abuse by undercover police, US rendition flights and, most recently, corruption at the very top of UK football. These investigations often involve activity that would, under any other circumstances, be unethical violations of privacy or unlawful conspiracy. Sometimes they involve the journalist engaging in or soliciting criminal conduct.

Investigative journalists have a get-out-of-jail-free card if their work is “in the public interest”. Their targets can merely hope that the Crown Prosecution Service (CPS) will decide that the same public interest is not served by prosecution. While this has sometimes rescued police officers, soldiers and government agents, it has conspicuously failed to save MPs, celebrities or sportspeople. And this is because the CPS notion of public interest is very closely aligned with that of the tabloid press.

The law governing state entrapment seeks to find the line between legitimate crime detection and unacceptable crime creation. It was settled in 1996 in R v Latif, and reviewed in 2001 by the House of Lords in R v Loosely. The rule is that state agents may present the defendant with an unexceptional opportunity to commit a crime, while behaving like ordinary members of the public. Police officers must act in the course of an investigation that is officially authorised, based on a reasonable suspicion that offences are already being committed, and properly supervised.

If these requirements are not met, the court may stay proceedings to avoid endorsing behaviour that threatens basic human rights or the rule of law. The problem is that most of this protection simply does not apply to non-state entrapment, where any inducement is allowed unless “it would be an affront to the public or offend ordinary notions of fairness”. The case of former X Factor judge Tulisa Contostavlos was a prime example, demonstrating that although a police officer cannot mount a case based on a £3.5m inducement, a journalist can, provided he or she has a reasonable suspicion that offences are already being committed.

The “Fake Sheikh” Mahmood’s approach was to use a technical team to record “everything”. This helped remove the focus from Mahmood and ensured that awkward questions about his character would be ruled inadmissible. The Tulisa sting produced 72 hours of recordings. It took hundreds of hours of listening to detect a whispered instruction to his assistant to take Tulisa to the toilets, off tape, and offer her £3.5m for acting the part of a drug dealer, something that Mahmood denied on oath but sound experts confirmed. Despite hearing the recording of Mahmood covertly offering a £3.5m film contract, the judge in effect decided this was perfectly fair.

The subsequent lies and attempts to get a driver to change his statement to bury evidence of Tulisa’s dislike of hard drugs was Mahmood’s attempt to hang onto his claim that she was already a hard drugs dealer before he came along.

An attempt to use the fairness provisions of the Police and Criminal Evidence Act was also rejected by the trial judge. Mahmood was even able to exercise journalistic privilege to shield the identities of the other journalists involved in the sting, including the mysterious woman who made the unrecorded and disputed offer of £3.5m in the toilets. As we now know, the law was wholly unequal to the task of protecting the public from a dishonest and manipulative conman who scammed not only his victims but also the public and even, it is said, his employers.

The other critical question is why the Crown Prosecution Service (CPS) simply accepted Mahmood’s evidence. It was clear that the integrity of the entire process rested on his being an honest witness. The trial judge described Mahmood as “the sole progenitor of [the] case, the sole investigator, the sole prosecution witness [and] someone who appears to have gone to considerable lengths to get Ms Contostavlos to agree to involve herself in criminal conduct”. What checks did the CPS make?

The answer to that question is not “absolutely none”. It is in fact “they were totally indifferent”. CPS London were not only sent a dossier of Mahmood’s past conduct in such investigations, much of which was appallingly and quite evidently dishonest, but given periodic updates as further material came to light. At no point did it regard it as being in the public interest to prevent this shabby fraudster from using the justice system for his own ends. The failings of the CPS in every area are sufficiently serious to warrant a public inquiry of its own.

We need a clause in the next Criminal Justice Bill that offers such defendants the same protections against entrapment by journalists, and the same disclosure rights that they would receive in a police investigation.

But the most urgent step is for the Government to get on with part two of the Leveson Inquiry, whose remit was to include “the extent of unlawful or improper conduct within News International, other media organisations or other organisations”. One of its outcomes should be a clear statement of the principles to govern collaboration between the police, the CPS and investigative journalists. Only then can people like my client be assured of the rights and protection they need.

Ben Rose was the lead solicitor on Tulisa Contostavlos’s defence team