Heads will not have to tell parents when a teacher uses force against their children, ministers have said.
The Government has scrapped a legal requirement for schools to record "significant incidents".
However, teachers' leaders have warned that the change leaves staff open to false accusations.
The Government has also axed another law, due to come into force in September, which obliged schools to work together to improve behaviour and attendance.
The Department for Education said the changes have been made to reduce bureaucracy. But NASUWT general secretary Chris Keates said parental confidence in teachers will be "diminished".
"There is a very real danger that failure to record and report incidents where force is used to control or restrain a pupil could mean that an allegation that is made, possibly years after the original incident, will be extremely difficult for a school to contest," she said.
Former "behaviour tsar" Sir Alan Steer called the change "lunacy", adding: "It certainly won't be Michael Gove and Nick Gibb standing up in court when a poor teacher is accused of assault."
Sir Alan also spoke out against the scrapping of the obligation for partnerships, which he said had a "dramatic" effect, helping teachers spot problems early. In a report published last year, he found permanent exclusions dropped by 26 per cent at a London school when partnerships were in place.
"Revoking this is a huge mistake, partnerships work extremely well and children will lose out," Sir Alan told The TES. "The new Government has not got a coherent strategy for behaviour, just a set of prejudices."