"There’s been a lot of pressure for some time to do something about the activities of the Revolutionary Guard Corps," Jonathan Hall KC told Iran International.
But while political calls to act had grown louder, he said the more important factor was the number of alleged Iranian plots disrupted by Britain's intelligence services and the public concern they generated.
"If you listen to what the director general of MI5 has been saying, there's been an extraordinary number of plots in the last few years that the intelligence services have had to disrupt and deal with," Hall said.
The government says MI5 identified at least 20 potentially lethal Iran-backed plots against people in Britain over the course of a year. It says the IRGC has used proxies and criminal networks to target Iranian dissidents and members of the Jewish community overseas.
Terrorism law 'never suitable'
Hall said the government had wanted to take stronger action against the IRGC but could not simply proscribe it under the Terrorism Act 2000 because the legislation was never designed to apply to the military or intelligence institutions of another state.
"The Terrorism Act was never suitable," Hall said. "It was never designed to deal with state bodies."
The Terrorism Act allows the government to proscribe organizations, making membership and various forms of support criminal offences. Hall said Parliament had never intended those powers to be used against the official institutions of foreign states.
The home secretary commissioned Hall in December 2024 to examine whether Britain's counterterrorism powers could be adapted to address state threats. His review concluded that they could not and instead recommended creating a separate designation regime under national security legislation.
"So rather than proscribing the IRGC or any other state body under the Terrorism Act, there's now a new piece of legislation," he said.
The National Security (State Threats) Act 2026 received royal assent on July 8, amending the National Security Act 2023 to allow the home secretary to designate bodies involved in foreign power threat activity where necessary to protect the UK's safety or interests.
The government laid draft regulations before Parliament on July 13 to designate the IRGC, the Iran-linked Islamic Movement of Companions of the Right and Russia's GRU Volunteer Corps. The House of Commons approved the regulations on Wednesday, while the House of Lords is due to consider them on Thursday.
The designations cannot take effect without the Lords' approval.
Targeting paid proxies
Hall said the primary aim of the new framework is to deter people in Britain from accepting money to conduct surveillance, violence or other activities on behalf of the IRGC.
"We know that the way that the Iranian regime operates in the UK is usually through proxies," he said. "These are individuals obviously willing to take money to carry out certain conduct."
He said the legislation could apply to someone paid to conduct reconnaissance outside the home of a television journalist, follow and stab an Iranian dissident or set fire to a synagogue.
A person could face prosecution if they knew, or should reasonably have known, that their conduct was likely to assist the IRGC.
"It's about credibly saying to people who might take £500, £1,000 or whatever to do that sort of thing: you are at risk of committing a National Security Act offence," Hall said.
"The desire is that people should be deterred. And, of course, if they do carry out that sort of proxy activity, they will then go to prison for a long time and be convicted under an exceptionally serious piece of legislation."
The law creates offences relating to supporting or assisting a designated body, or receiving a material benefit from one, carrying maximum prison terms of 14 years.
People convicted of espionage, sabotage or foreign interference carried out for, on behalf of, or with the intention of benefiting a designated body could face life imprisonment. Prosecutors would also no longer have to establish a separate foreign-power connection in every case.
Conscripts not criminalized
Hall said the legislation deliberately avoids creating a criminal offence of membership in a designated state body, partly to avoid penalizing Iranian men who had to complete military service in IRGC units.
"This conscription point was quite influential on me when I did my analysis," he said.
Hall said membership of a proscribed terrorist organization could be criminalized because an individual generally chooses whether to join or remain in such a group. That approach would be inappropriate for someone compelled to serve in a state institution.
"That obviously wouldn't be right in the case of someone who's got no choice about whether they are a member of a state body," he said.
Asked whether the law could affect Iranian men required to complete military service in IRGC units, Hall replied: "The answer is this law doesn't apply in any way."
Protecting communities targeted by the IRGC
Hall said the new measures are intended to make it riskier for IRGC proxies to target journalists, Iranian dissidents and members of the Jewish community in Britain.
"It's not just about finances," he said. "What it does is it provides a little bit extra."
"From the perspective of journalists and dissidents and Jews in the UK, the point actually is to make it more risky for proxies to act and to make it tougher for them to operate."
Prime Minister Keir Starmer said the government would not allow foreign states to use Britain to spread fear, division and violence, while Home Secretary Shabana Mahmood said the new powers would make it easier to prosecute people carrying out hostile activities on behalf of Iran, Russia and other foreign actors.
The government has cited alleged IRGC-linked plots targeting two Iran International journalists in Britain as an example of the activity the new framework is intended to address.
It also says the Islamic Movement of Companions of the Right claimed responsibility for seven attacks against sites linked to Jewish and Israeli communities and Persian-language media between March and May, with members of the IRGC's Quds Force "almost certainly" directing the group's activities across Europe.
For Hall, however, the legislation's purpose is ultimately straightforward: to close a gap in British law by giving authorities a tool specifically designed to tackle hostile state organizations—something he says terrorism legislation was never intended to do.
