Defendants may be banned from having lawyers of their choice under proposals slipped out by the Government yesterday.

This may be contrary to the Human Rights Convention, which says that everyone charged with a criminal offence has the right to defend himself through legal assistance of his own choosing.

In a policy document published yesterday, Lord Falconer, the Lord Chancellor, said the Government proposed to give judges new powers ordering defendants to change their lawyers "where this is in the interests of moving the trial to a just outcome".

The proposals, buried in a paper called Delivering Simple, Speedy, Summary Justice, are said to be aimed at reducing delays in cases involving several defendants. Where a number of people have been charged with conspiring together to commit a crime, defendants sometimes claim that only the others were responsible - the so-called "cut-throat defence".

In such cases, the paper says, "there is often a serious risk of a conflict of interest where one firm of solicitors acts for a number of defendants".

It continues: "We propose to give the judiciary new powers through regulations - which we will aim to introduce in the autumn depending on the outcome of consultation - that will give trial judges the power to order a change in defence representation where this is in the interests of moving the trial to a just outcome."

The new power may be exercised at the request of the prosecution. Lord Falconer's paper makes it clear that defendants will not have an automatic right to be heard before being deprived of a lawyer, although the judge may choose to listen to them.

"The judge will have discretion to receive representations from parties in the case (both prosecution and defence), and will refer to professional rules on capacity and conflict of interest," the paper says. "Should the judge order a change of representative, the defendant will have a set period in which to make their choice as to their preferred replacement."

The paper does not say what will happen if the defendant cannot find a replacement before the deadline.

The power could also be used in terrorist trials, where several defendants often choose the same solicitor. There have been concerns that this has delayed police investigations.

Lawyers said the restrictions may fall foul of the Human Rights Act. Article 6.3 of the Human Rights Convention says: "Everyone charged with a criminal offence has the following minimum rights. . . to defend himself in person or through legal assistance of his own choosing".

Ministers have no power to introduce regulations that are incompatible with the Human Rights Convention, unless required to do so by statute. Such regulations are unlawful and would be set aside by the courts.

Other proposals in the paper include piloting "next-day justice", defined as defendants appearing in court within three days of an offence.

The Government also wants to try out what it calls "courts on the move", which means setting up occasional courts in fixed buildings such as town halls and community centres.

The Magistrates' Association said it was ironic that the Government was "taking courts back into communities". Ministers had been closing courts since the 1990s, reducing the ability of magistrates to deliver local justice. It was also concerned about plans to divert from the courts low-level offending such as summary motoring cases and television licence default.

Cindy Barnett, the association chairman, said there was "a world of difference between keeping someone from the court process where the matter is really minor and dealing with a more serious crime without taking it to court because it is speedier and simpler".