A new report from Queen Mary University of London and Defend Our Juries says 286 climate and Palestine-solidarity activists were jailed in England and Wales for protest activity, with those cases adding up to 136 years of prison time.

David Whyte, one of the researchers behind the work, said the sentences were not ordinary punishments for ordinary offences. The report, due to be launched on Tuesday, says the scale and length of custody show protest is being met with a severity once reserved for far different conduct.

In the 256 cases where the researchers had enough information to calculate time served, the average detention period was 28 weeks. One in three protesters in the report was jailed for six months or more, and one in five received more than a year behind bars. The numbers, the researchers say, show custodial sentences for direct action and civil disobedience have moved from rare to routine, and that they are now being used with increasing length and frequency.

Whyte said the pattern was especially stark in cases tied to climate protest and solidarity with Palestinians. He argued that what was happening was “profoundly political,” and said protesters were often reflecting a majority view rather than a fringe one. The report also says anti-protest legislation in England and Wales, police powers, civil law injunctions, judges removing legal defences and unusually long sentences have all fed the rise.

Remand, the researchers say, has been the first line of attack. In 60% of the cases they examined, final sentences were more lenient than the time people had already spent in custody waiting for trial, a gap the report says chilled protest and civil disobedience before cases were even heard.

Contempt of court accounted for 40% of the imprisonments in the report. Those cases included breaches of judge’s orders in 8% of the total, and breaches of civil injunctions obtained by private companies or public authorities in 32%. Whyte warned that the danger lies in turning what begins as a civil order into a criminal penalty, saying private companies can effectively impose injunctions that end in jail terms.

The report singles out the Filton 24, charged over a Palestine Action direct action protest at a factory near Bristol run by the Israeli weapons manufacturer Elbit Systems. The accused spent up to 18 months in jail before most were bailed, even though the standard pre-trial limit is six months. All but one of the Filton 24 were released after the first six defendants were cleared of aggravated burglary, and two of those six were later acquitted of criminal damage.

The Filton case remains unfinished. Eighteen more defendants due to stand trial over the events at Filton still face other charges, leaving the wider legal fight over protest, injury and public order unresolved even as the report argues Britain has already crossed into a new phase of punishment for dissent.