Five people have been given jail sentences totaling more than 14 years for their part in a violent Kill The Bill protest in central Bristol.
Bristol Crown Court heard police were "dehumanised" when violence broke out in Bristol city centre following a peaceful protest in March this year.
The court heard police were kicked, stamped on and urinated on while vehicles were set on fire and a neighbourhood police station vandalised.
Kane Adamson, Brandon Lloyd, Stuart Quinn, Kain Simmonds and Yasmin Schneider are the first to be convicted in what remains the biggest-ever investigation Avon and Somerset Police have ever carried out.
Adamson, Lloyd, Quinn and Simmonds pleaded guilty to a charge of riot at an earlier hearing. It is the first time such a charge has been made in the South West.
Schneider earlier admitted outraging public decency.
The sentences given out at Bristol Crown Court on Friday 30 July
Adamson, aged 21: Three and a half years
Lloyd, aged 21: Three years and 11 months
Quinn, aged 46: Three years and three months
Simmonds, aged 18: Three years and three months
Schneider, aged 25: Five months
His Honour Judge James Patrick told them their actions were "menacing and sinister", saying they sought to "dehumanize" police officers.
All charges related to a riot in Bristol on Sunday 12 March which saw protesters clash with police outside Bridewell Police Station.
Police vehicles were set alight, windows smashed and property daubed with graffiti. The total cost of the damage was put at around £250,000.
Surrounded in the dock at Bristol Crown Court by five security guards, the rioters heard prosecutor Richard Posner say their actions were "stupid, irresponsible and dangerous".
He said the day began with a peaceful protest against the Police, Crime and Sentencing Bill which is currently going through Parliament.
Mr Posner said the event was later "hijacked" with "protesters being replaced by a mob".
He told the court police officers were stamped on and punched, hit with batons and glass bottles and fireworks, leaving them fearing for their lives.
"In their heads, officers said goodbye to their families, they feared they would not be going home that night," added Mr Posner.
"The protestors thought they were untouchable and beyond detection. Each defendant knew what they were doing."
He said 44 police officers were injured that night before playing the court videos of CCTV camera shots and police body-worn camera footage of the violence.
Avon and Somerset Police have arrested 75 people since a series of protests in Bristol in March. A further 37 people are still being sought.
Ch Supt Carolyn Belafonte said: “What happened on the night of Sunday 21 March was nothing short of reprehensible.
“Dozens of people came together and acted as a mob to attack and injure police officers, set fire to police vehicles and damage a neighbourhood police station."