Arresting Palestine Action supporters is necessary to deny the group the “oxygen of publicity", the UK’s independent reviewer of terrorism laws has said.
Jonathan Hall has backed the designation of the group as a terrorist organisation and drawn parallels with ISIS and terrorist groups in Northern Ireland.
The group was proscribed after its activists broke into a Royal Air Force base and attacked aircraft it believed were being used to help Israel in its war in Gaza.
In response, some of its supporters have joined demonstrations in central London to defy anti-terrorism legislation to deliberately get themselves arrested.
Figures from London's Metropolitan Police after a rally this month revealed half of those arrested were over 60 reveal, leading to the accusation that the UK is criminalising mainstream supporters of the Palestinian cause.
Mr Hall, a barrister who was appointed independent reviewer of terror laws in 2019, told the BBC: “I don’t really think that as a matter of principle, how someone looks, what age they are, what they appear to be, what their job is, should make a difference to the principled application of the law.
“If you accept, and I certainly do, that Palestine Action ought to be prescribed, then you need to make sure that it doesn't have the oxygen of publicity."
He said it was “vital” that people have an opportunity to protest about the cause of Palestine but compared placards seen on Palestine Action marches to symbols of ISIS, and republican and loyalist terrorists in Northern Ireland.
The black flag of ISIS “being marched down the street ... would have, perhaps, a recruiting effect, might have certainly have an intimidatory effect”, Mr Hall said.
He added that “it’s something that we're quite familiar with from Northern Ireland, masked men appearing to be supporters of the IRA” or flying the flag of loyalist terrorists “in a mixed housing area, signalling to Catholics that they should leave”.
Former Supreme Court judge Jonathan Sumption said on Monday he also believed proscribing Palestine was correct but added that arresting people for expressing support for the group was wrong.
He said carrying placards or wearing T-shirts with a logo “seems to me to belong in the domain of free speech and private opinion”.
“The problem is that if cast the net of support too wide, we're actually going to discredit what is good about this law, which is that it empowers the government to proscribe really wicked organisations like Palestine Action.
“I entirely agree that sensible people would make their views on Gaza known without supporting the methods of this particular organisation, and they aren't behaving very sensibly. But that doesn't seem to me to be enough to justify locking them up.”
Palestine Action has been allowed to challenge the UK government decision to designate it a terrorist organisation and a hearing is due to take place this year.
