The co-founder of Palestine Action has said the ban on the group “massively backfired” and called for its proscription to be suspended after the high court found it to be unlawful.

Three senior judges ruled on Friday that the ban was disproportionate and constituted very serious interference with the rights to protest and free speech.

But the proscription order remains in place pending arguments from lawyers for the home secretary, Shabana Mahmood, on why it should not be lifted, meaning the fate of more than 2,500 people remains in limbo.

Huda Ammori, who co-founded Palestine Action in 2020 and brought the successful legal challenge, said her lawyers would resist Mahmood’s attempts to retain the ban while the home secretary tried to appeal against the judgment.

Ammori said: “Considering the thousands of people who are going through the criminal justice system are being prosecuted for holding up signs saying: ‘I oppose genocide, I support Palestine Action’ and the chaos that’s created, it’s ridiculous to even try and maintain an unlawful ban.

“The logical next step is for either the [proscription] order to be quashed, and, if not quashed completely, for the effect of the proscription to be stopped whilst the government attempts an appeal.

“This is a huge, huge step forward, and we’re closer than ever to getting the ban lifted. So even though it didn’t happen immediately, I have faith that it’s going to happen quite soon. The ban has been proven unlawful from its inception so the fact that we haven’t been de-proscribed immediately – we can wait a little bit longer.”

Saying that the government would appeal on Friday, Mahmood added: “The proscription of Palestine Action followed a rigorous and evidence-based decision-making process, endorsed by parliament.”

More than 500 of the 2,500-plus placard-holders have been charged under section 13 of the Terrorism Act but their cases have been delayed while the outcome of the judicial review was awaited. They took part in a civil disobedience campaign of mass protests defying the ban and earned a glowing tribute from Ammori.

She said: “It’s just been incredible, it’s been so inspiring and moving to see how many people have been inspired to resist this ban, to defy it.

“When I first heard about the proscription going through, it’s just like a ton of bricks, and then when you see the amount of solidarity and support – it’s incredibly uplifting. And I won’t say ‘I think’ – I know this victory is in huge part thanks to them.”

The judges described Palestine Action as “an organisation that promotes its political cause through criminality and encouragement of criminality”, a definition seized on by Mahmood. But they found that, as such, most of its activities could be dealt with by criminal law, and did not amount to terrorism – meaning that proscribing the group could not be justified given the interference with protected rights.

Ammori said winning on the free speech and right to protest ground – one of two on which she was successful – was important. If she had succeeded only on a procedural ground, such as the failure to consult Palestine Action before the ban, which was rejected by the judges, it would have been open to Mahmood to consult and still reach the same decision to proscribe.

But the result was an emphatic one after months that Ammori said had taken a personal toll on her. “It’s not easy to be labelled or smeared as a terrorist, to see that something that was made and founded in order to disrupt the Israeli weapons industry, to stop the greatest crimes happening against the Palestinian people, can be labelled as a terrorist organisation,” she said.

“I think with my background being Palestinian and Iraqi, it’s not the first time I would have had the kind of slur but I remember the first month or two, every time I heard the words terrorist organisation on a news programme, you can’t connect with that. It just makes you feel sick to your stomach to hear that’s how they describe Palestine Action.”

Ultimately, she believes it was an own goal for a Labour government bent on destroying the organisation.

“This has made Palestine Action a household name,” she said. “It has sparked outrage among thousands, if not tens or hundreds of thousands of people across the country and across the world and it has increased the support for direct action massively. It’s now proven that they did all this unlawfully, did all those arrests unlawfully. That’s a huge attack on people’s rights and I think that has massively backfired on them.”