The government is publishing new guidelines for parents and teachers in England which it hopes will mean more children go on school trips.
The Department for Education has told schools and local authorities to ditch "unnecessary paperwork", and has cut its 150 pages of guidelines to eight.
Education Secretary Michael Gove said it would mean a "more common sense approach to health and safety".
But teaching unions said many rules were there for good reason.
"What we wouldn't want to do is to see a reduction of guidance which could lead to a lot more accidents," said Amanda Brown, of the National Union of Teachers.
"What we want is advice which is very clear and straightforward but long enough to cover enough of the detail so that people do feel secure."
The NASUWT teachers' union said cutting back guidance could reduce parents' confidence and make teachers more nervous about school trips.
'No way to avoid risk'
The Health and Safety Executive (HSE) said it hoped the new guidelines would dispel legal "myths".
HSE chairman Judith Hackitt told the BBC it was "time to out those who hide behind red tape and procedures and often blame us and health and safety as the reason why they can't do these things".
She said the set of guidelines had ended up being overly bureaucratic because of a fear of civil litigation, cost-cutting and because it was an easy way to avoid work that was regarded as more difficult.
Miss Hackitt said teachers were intelligent people and they should be trusted to use their common sense.
She said parents needed to realise their children also needed to learn how to manage risk.
Ministers said school trips could broaden children's horizons but fear of prosecution was too often used as an excuse not to organise them.
In the past five years only two cases had been brought against schools for breaches of health and safety law on a visit, they said.
Francis Gilbert, a secondary school teacher for 20 years, agreed permission and insurance paperwork could often put teachers off organising school trips.
"At the moment people like me, if I was to put hand on heart, haven't taken pupils on school trips because it's such a palaver and you are worried that you'll get sued if something goes wrong, so the pupils miss out."
A Labour Party spokesman said health and safety rules needed to be applied sensibly.
"There is no reason - and never was - why children should be prevented from going on school trips by over-enthusiastic misinterpretation of rules," he said.
Employment minister Chris Grayling said a change in approach was important.
"We've got a crazy situation at the moment where, very often, headteachers and teachers think that actually the rules are such that it's not a good idea to plan school trips.
"There's too much bureaucracy, too many health and safety rules and a risk of prosecution if something goes wrong," he told the BBC.
Mr Grayling said if teachers used common sense in planning trips the government would support them.
Only in cases where teachers were "utterly, grossly negligent" would there be legal implications, he said.
The new guidelines clarify that written parental consent is not needed for each activity and encourage schools to use a new one-off consent form signed once when a child starts at a school.
Mr Gove said: "Children should be able to go on exciting school trips that broaden their horizons.
"That is why we are cutting unnecessary red tape in schools and putting teachers back in charge.
"This new, slimmer advice means a more common sense approach to health and safety. It will make it easier for schools to make lessons more inspiring and fun."
The Department for Education says the revised guidance:
- Summarises the legal duties of head teachers, governing bodies and local authorities on health and safety, and covers activities that take place on and off school premises
- Makes clear that a written risk assessment does not need to be carried out every time a school takes pupils on a regular, routine local visit, for example to a swimming pool or museum
- Tackles "myths and teachers' fears about being prosecuted" by making the law clearer
- Clarifies that parental consent is not necessary for pupils to take part in the majority of off-site activities organised by a school, as most of these activities take place during school hours and are a normal part of a child's education.