The government's plans to open up legal aid to competition will have devastating consequences for vulnerable people and the profession.

For a baby like Joe, the government's legal aid reforms could be a disaster. Taken to hospital, he was found to have a broken leg, the result of a non-accidental injury. His mother was also physically abused by his father. Joe was put under a local authority care order. With much support, facilitated by a solicitor, Joe was eventually returned to his mother and the parents separated. Without good legal representation, funded by legal aid, Joe could have been taken into care for the rest of his childhood, with the state footing the bill.

But the Joes of the future may struggle to find legal aid help. According to June Venters QC, who has extensive experience in legal aid, if proposed government reforms to legal aid go through she would probably not be able to afford to take on a case like Joe's. That is, if she was still in business at all.

Venters says the consequences will be devastating, damaging those who provide legal aid to poor and vulnerable people. Legal aid is one of the cornerstones of a fair and decent society. It gives disadvantaged people access to justice, whatever their income. Solicitors go into legal aid work because they care - not to make money. But now this money is being reduced.

Fixed fees

The government wants to pay legal aid solicitors and other legal aid advice services - such as citizens advice bureaux and legal centres - through a system of fixed fees and competitive tendering. They are currently paid by the hour, and Venters says: "Under the new proposals, every legal aid practice is going to suffer a serious reduction in income - by as much as 50%. It's just not viable." Many will simply stop doing legal aid work.

This could lead to advice deserts around the country where there are no specialist firms. Poor and vulnerable people who need advice either will not get it or will not get the quality of advice on which their case may turn. Steve Hynes, director of the Law Centres Federation, says: "Law centres would rather walk away than be part of a system that will not pay for good quality casework for poor and vulnerable clients." Significantly, What Price Justice?, the Law Society campaign against the reforms, is supported by Mind, NSPCC, Shelter, the Refugee Council and Advice Services Alliance, among others.

The government is trying to keep costs in check by turning the buying of legal aid into a market. The problem is, unlike a real market, they are the only buyer. Every legal aid practice or service will, from October 2008, have to competitively tender for a contract. But what happens to the legal aid practice that does not win? It cannot wait around for the next auction. It will close, and the solicitors will go into private practice.

Another fear is that the small-scale advice centre or ethnic minority solicitors that have a relationship with a specialised part of the community will be forced to close and those clients, who may not have English as their first language, will be even more socially excluded.

But it is fixed fees that are so unfair. With particularly disadvantaged clients, some cases are likely to be more complex, and therefore take longer. Clients may have learning difficulties, mental health problems, drug addiction or not speak English as a first language. Many advice centres talk of clients walking in with several carrier bags of paperwork, which takes hours to unpick. But however complex the case, the fee will be the same. What is the incentive to take these on?

The fear is that straightforward cases will be "cherry picked", and that those disadvantaged people who need the most help will be least likely to get it. Vera Baird, minister for legal aid, argues that costs should go in "swings and roundabouts", but this will not work in inner-city areas, where there are more of these clients.

The government argues that the legal aid budget has increased from ?1.5bn in 1997 to ?2bn and that this is "unsustainable". But if the legal aid budget has increased, it is not because of fees paid to lawyers. Legal aid solicitors are already underfunded. Most criminal lawyers have not had a fee increase since 2001. Many practices already subsidise legal aid work and rely on continual overdrafts. Indeed, the government's own in-house public defender scheme recently found its costs running at 40%-90% higher than those of the high street firms. In the past five years, over a quarter of criminal law firms and 670 civil firms have closed. An estimated 800 more are expected to close if the reforms go through. As Desmond Hudson, chief executive of the Law Society, says: "Legal aid solicitors will soon be rarer than NHS dentists."

So what is making costs rise? The government points to the 37% increase in criminal legal aid spending, and wants to reduce it to boost spending in civil and family legal aid. But the budgets should be treated separately. It is not a see-saw, where criminal spending goes down so civil spending goes up. The criminal legal aid budget has increased because 3,000 new criminal offences have been introduced since 1997. Likewise in civil law, where more procedures have been introduced, but the bottom line is that there are more needy people and more cases.

There are other factors across the legal system forcing budgets up: the cost of the Legal Services Commission, which implements legal aid, has risen by ?47m. And fees for medical experts at court are increasing; they can charge ?1,500 a day.

Given the consequences for society, it is alarming that these changes can be introduced without parliament's scrutiny. The Legal Services Commission last November announced its plan, Legal Aid Reform - The Way Ahead, following consultation after Lord Carter's review of buying legal aid. The Way Ahead lays out how the changes will be implemented, with fixed fees being introduced in October.

Mass of opposition

But there is a mass of opposition. Lord Justice Wall, a senior family judge, called the reforms "devastating"; the Mental Health Lawyers Association warns of "meltdown"; Hudson says it is the "destruction of legal aid"; more than 100 MPs, across all parties, have signed a motion calling for a Commons debate, and it is hoped a select committee report will increase pressure on the government.

The result of all this? Those working in legal aid feel demoralised and undervalued. There is a crisis in the recruitment of new young solicitors. Who will want to work in legal aid in the future? But it is, of course, disadvantaged and vulnerable people who will suffer most.

The lord chancellor says that "legal aid is one of the pillars of the welfare state". But unlike those other pillars, health and education, legal aid has fared badly. In the past 10 years, spending on health has increased 100%, education by 88% and legal aid by just 27%. The government should put its money where its mouth is by funding legal aid properly and listening to the providers it relies on. You cannot have a Rolls-Royce service for Lada money.

It took many years to create the legal aid system we have today. It will take only a matter of months to destroy it.

? Tracy Cook is a documentary maker and produced the BBC1 series, Law Women. A debate, Legal Aid: What Future for the Fourth Emergency Service?, is being held at the Keyworth Centre, South Bank University, London SE1 OAA, tomorrow at 7pm. Further details at younglegalaidlawyers.org