The government's school reform plans for England are facing another test in the Commons as the Education Bill enters its final stages.
Good schools would be encouraged to expand
After an earlier Labour backbench rebellion, the education secretary says the prime minister may have to rely on Tory votes to get the reforms through.
What are the main aims of the reforms?
Ministers say they want to give schools more freedom. Parents, businesses and voluntary groups would be able to set up new "trust" schools - technically, foundation schools - whose foundation could appoint a majority of governors.
They will take control of their own buildings and land, directly employ their own staff, and will set and manage their own admissions criteria, while remaining state maintained schools.
The government believes that the way to raise standards is to encourage innovation in schools. It believes this does not happen under the bureaucratic and "stifling" control of local councils.
So will trust schools be like independent schools?
In a way they are modelled on independent schools. Like private schools, they will develop their own special characteristics and ethos and will not be part of the local council network of schools.
But they cannot charge fees. And although businesses can set up and run trusts, they cannot make profits from doing so. Neither will trust schools receive extra funding, the government says.
Can they select pupils?
Trust schools will also have the same freedoms as foundation schools and voluntary-aided schools (many are church schools) to set their own admissions criteria. So, for example, they could give priority to pupils who support a particular religious ethos.
It is this freedom which has led some critics to fear that this would open the door to covert selection.
Like all state-funded schools, trust schools must take account of the code of practice on admissions. They are also subject to rulings by the Schools Adjudicator if they break this guidance.
The government is proposing to change this so all schools must "act in accordance with" the code rather than simply "have regard to" what it says.
Many, though not all, categories of specialist school can select up to 10% of pupils by aptitude for their specialist subject, though few do.
A specialist trust school would be in the same position but would not otherwise have greater powers of selection.
What about interviews?
Interviewing prospective pupils and their parents - currently deprecated in the admissions code of practice - is to be outlawed.
In practice hardly any school uses interviews. But moves to stop the London Oratory doing so failed, showing the code lacked teeth.
Will schools have to become trusts?
No - although ministers want failing schools to be forced to be taken over by trusts.
One of the rebels' complaints has been that the white paper said any new schools would have to be trust schools.
Ministers now say that when a new school is to be built - which does not happen often anyway - councils would be able to propose an ordinary community school.
The process would still be subject to a competition overseen by the Schools Adjudicator, and the education secretary would still retain a veto.
What would it mean for local authorities?
Ministers are talking about giving them "strategic oversight". Essentially they would have stronger powers to regulate the planning of school places.
Local authorities would also host "forums" of all the schools in their area to agree a co-ordinated plan for schooling, including admissions.
Such forums already exist but vary hugely across the country. The compromise plan would let the forums refer a school suspected of breaking the admissions code to the Schools Adjudicator.
At present only other admissions authorities - schools or councils - can object.
Schools adjudicators pass judgement on schools' admissions policies but cannot intervene independently - and know of breaches of the code that some councils do not refer to them.
Will the plans mean more choice for parents?
The government says it will put "parents in the driving seat" and councils will have to listen to parental views when deciding whether or not to create a new school in the area.
Popular trust schools will be encouraged to expand, creating more places and theoretically more choice for parents. But if schools are full, there can be no guarantee of places for local parents.
By setting their own admissions criteria, trust schools would not be restricted to taking only those pupils living nearest to the school.
It is also alleged that trust schools would "squeeze out" poorer or less able pupils.
Some religious schools, which select on non-distance criteria, point out that they get a broader social intake by doing this than they would by just taking local pupils. Selecting pupils by distance from home to school can lead to selection by house price.
So how many schools are likely to seek trust status?
It is early days yet, but so far there has been no rush of interest from schools. This is perhaps not surprising, since the government has sought to reassure its own backbenchers by insisting there will be few special privileges for trust schools.
Specialist schools (now at least 75% of all secondary schools in England) already have the benefit of involving sponsors and the 1,000-plus foundation and voluntary aided schools already manage their own admissions.