Andrew Parker, the new MI5 chief, is right to be deeply worried by the Snowden revelations. The new availability of information on the web is opening up secrecy like a knife into an oyster. However, Anthony Glees, head of the centre for security and intelligence studies at Buckingham University, ignores the fact that secrecy in this country is overprotected and under-regulated when he suggests the Guardian should be prosecuted for putting this under the microscope.

Britain has utterly failed to prepare itself for openness when dealing with politically sensitive issues such as terrorism, or the involvement of their secret agencies in the covert gathering of information. We rarely hear from the intelligence agencies' chiefs; and ministers glide over the threats, never explain their relationship with those agencies, and retain an obviously inadequate system for their supervision. As a result, as long as ministers continue to authorise the agencies' eavesdropping, surveillance, and informant approval, the public will believe there is an unhealthy relationship between them. That scepticism is made worse by the communications data bill's proposal that the agencies themselves control their mining of communications data.

Against this background it is hardly surprising that the Snowden revelations have not been met by the public antagonism one might expect when national security has been compromised. The government must regain the initiative. A first and necessary step is to leave the authorisation of eavesdropping, surveillance and informant approval to the judiciary. This would mean that applications to carry out such covert activities would have to be made by the agencies direct to a judge. This would reduce both the risk and the perception of collusion or political interference.

Government may argue that all this is unnecessary as there is already adequate oversight of the agencies. It is true that oversight has improved now parliament itself is in charge of overseeing the agencies. However, that oversight is ex post facto and is, on the admission of former oversight committee chiefs, both inadequate and subject to political pressure. Moreover, it is no substitute for independent judicial authority.

As a bonus, if judicial authority were given for telephone and electronic intercepts, evidence thus collected could be used to prosecute terrorists, as happens in the US. The current refusal of the UK government to use intercept evidence would then look even more unwise.

This concept of judicial authority for intrusive covert surveillance is not new. Many jurisdictions adhere to it. In the French legal system, a judge supervises covert targeted operations and determines the civil rights balances involved. This way, both the public and the agencies are protected, and at any subsequent trial the evidential uncertainties have already been excluded. In the UK such a procedure would obviate the need for secret courts to determine civil proceedings and reassure the public that fair trials remain a baseplate of our society. It is a system that needs to be introduced to all the UK agencies' covert targeted operations.

The government could then turn its attention to the vital job of informing the public. Unlike in the US, the British public do not get to see the intelligence agencies' chiefs grilled by the oversight committee, nor do they see those chiefs and the law enforcement agencies being interviewed together about their objectives and the tools they need to achieve them. The public have a right to see and hear this so that they can make up their own minds about the integrity of the leaders, the validity of their objectives, the need for the tools they use and whether the secrecy demanded is properly balanced.

Unless government takes this debate seriously, the British public's need to know what the intelligence agencies are doing will continue to shatter secrecy – and terrorism and organised crime will benefit.