A Met Police appeal against a ruling that it breached the rights of the organisers of a vigil for Sarah Everard has been rejected.
Two High Court judges dismissed part of the Met's case as "hopeless attempts to challenge reasoned factual conclusions" over the Reclaim These Streets event.
RTS cancelled its planned vigil after the Met said it would be in breach of lockdown restrictions.
A spokesperson said the decision was a "victory for women".
Despite the Met's successful opposition to the formal event, an unofficial gathering went ahead for the murdered marketing executive.
Dismissing the Met's case, Lord Justice Warby and Mr Justice Holgate said its lawyers must have misread the original judgment before launching the action.
They said of the original ruling: "The court applied and followed principles laid down by the Supreme Court and Court of Appeal.
"We do not believe there is a need for any further or more authoritative guidance for the purposes of lawful policing of protest in such cases.
"It is not arguable that we erred in principle and see no other reason to believe that the Court of Appeal would be prepared to adopt a different factual analysis."
The judges described some of the Met's proposed grounds of appeal as "hopeless attempts to challenge reasoned factual conclusions", while others involved "a misreading of one passage of the judgment, ignoring the overall context".
However, the force could still pursue a challenge by gaining permission to do so from the Court of Appeal.
BREAKING: the High Court has refused the police permission to appeal our win, saying that none of their grounds of appeal have a reasonable prospect of success— Reclaim These Streets (@ReclaimTS) April 11, 2022
Reclaim These Streets (RTS) said the appeal case "exposes the Met's total disregard for women's human rights to assembly and expression".
A spokesperson added: "The decisions and actions by the Met Police in the run-up to the planned vigil for Sarah Everard were unlawful, and the judgment sets a powerful precedent for protest rights."
The judgment should "reverberate widely", the spokesperson said, particularly in light of new powers to curb protests set out in the Police, Crime, Sentencing and Courts Bill, which was passed by MPs earlier this year.
RTS added that the Met should "stop wasting taxpayers' money" on appeals and instead invest in "measures to keep women in London safe".
Ms Everard, 33, vanished as she walked home in Clapham, south London, on 3 March. Her body was found a week later in woodland near Ashford, Kent.
Last month, the Met Police made the decision to appeal, in order to "resolve what's required by law when policing protests and events" in future.
"It's important for policing and the public that we have absolute clarity of what's expected of us in law," the force said in a statement.
"This is why we feel we must seek permission to appeal [against] the judgment in order to resolve what's required by law when policing protests and events in the future," the statement added.
Serving Met Police officer Wayne Couzens murdered Ms Everard after kidnapping her under the guise of an arrest due to a lockdown breach. He was sentenced to a whole-life prison term in September.
Addressing reporters outside the Old Bailey following his sentencing, Metropolitan Police Commissioner Dame Cressida Dick said she recognised that a "precious bond of trust" had been damaged by Couzens, who had "brought shame on the Met".