Seven people were arrested for failing to disperse after Bristol’s fifth Kill the Bill protest in less than a fortnight.
About 1,500 people took part in a demonstration from College Green to the city centre on Saturday afternoon.
Later, about 100 people blocked an entrance to the M32 at about 21:30 BST, before returning to the city centre.
Avon and Somerset Police implemented a dispersal order at about 00:00 after “minor disorder between protesters”.
Supt Mark Runacres said “an increasing number of protesters” in Bristol had worked with police liaison officers to ensure the main events on Saturday remained peaceful.
Supt Runacres said dispersing protesters on the motorway would have “presented an unacceptable risk” and “the safest thing to do was to allow the protest to run its course” in the city centre.
He added: “At around midnight there were several altercations between the small number of people who remained in the city centre.
“We never tolerate violence and so we made the decision to move people on.
“It’s disappointing that once again there were those who refused to listen to our requests to leave, and that we had to make arrests.”
Thousands of protesters also turned out at Kill the Bill protests in London, Birmingham, Liverpool, Newcastle, Weymouth and Bournemouth, amongst other places.
The Police, Crime, Sentencing and Courts Bill would give police in England and Wales more powers to impose conditions on non-violent protests, including those which are deemed too noisy or a nuisance.
Anyone refusing to follow police directions about a protest could be fined up to £2,500.
Former Labour leader Jeremy Corbyn addressed crowds in London’s Parliament Square and said the Police and Crime Bill was a “very dangerous, slippery slope”.
The Metropolitan Police said 26 people had been arrested at the London protest for a variety of offences including assault on police and breach of the peace.
A woman was arrested on suspicion of possession of an offensive weapon after a knife was recovered.
The force said 10 officers had been injured, although “none of these are believed to be serious”.