Words to a solicitor are like bricks to a builder -- the raw material of the trade.

So most solicitors are highly cautious about giving responsibility for the final form of words in a legal document to someone outside their firm.

For UK firms working internationally however, it is common practice: operating in English, they must employ the services of professional translators, mindful that an incompetent or careless translator can wreak havoc on their precisely worded drafts.Unfortunately, guidance on choosing a good translator is not easy to find.

Some firms have partially solved the problem by employing their own translators in-house.

London firm Warner Cranston runs a bilingual English/French department employing French lawyers as well as French-speaking British lawyers.

This makes sense for a firm doing around 10% of its business in French.Few British commercial lawyers have any knowledge of the languages spoken in growth areas such as eastern Europe, Russia and the Far East.

In any case, legal translation is demanding work and requires extremely high standards of fluency and linguistic ability.Most firms find themselves using external translators, and here the choice falls between going to a translation company or an individual freelance.

Making the choice is a real headache for solicitors: they know that their priority must be to ensure the quality of the translation, but it is difficult for them to judge how good a translation service is likely to be.

This makes it tempting to use one of the major translation agencies or companies which maintain departments of linguists to check the quality of their translators' work.RWS Translations is a big City translation house that claims 15 of the top 20 law firms as clients and has more than 50 in-house translators.

According to Charles Morris-Denholm, RWS's business development manager, the company's systems ensure the quality of its translations, and it was also the first translation company to win International Standards Organisation (ISO) accreditation for its management processes.Dibb Lupton Alsop uses Central Translations based in London.

James Glover, an assistant who recently handled a case in Liechtenstein, said the firm was very pleased with the agency's work.

But he agreed that it can be difficult for solicitors who are not themselves expert linguists to assess the quality of translation.A translation company also offers immediate service.

Individual freelancers will not always be available to work immediately.

Sean O'Connor, a leading independent French/English legal translator, says: 'Translators who are any good are usually busy for the next few days because they are in great demand.' Indeed, the top legal translators say they are successful because they are known individuals who can be relied on to produce top-quality work every time.Agencies and companies usually keep translators at arm's length from the client to prevent poaching.

But this means that when a firm goes to an agency, it will often have no idea who has actually done the translation.

This is particularly risky in long-running cases, where the consistency of terminology achieved by using the same translator throughout is vital.According to Ellen Moerman, a freelance Dutch, French and English legal translator and a trainee barrister, some firms decide to use an agency because they do not know where to find a freelance translator.

In fact, the translation industry's professional body, the Institute of Translation and Interpreting (ITI), maintains a network of legal, insurance and financial translators, and will usually be able to find a suitable translator.

The ITI admits members by examination and maintains a regulatory system aimed at ensuring high standards among its members.Some firms insist on having named individuals to carry out translations.

City firm Denton Hall keeps a list of individual translators on a database available online to all staff.

The firm's director of professional excellence, Paul Hancock, says: 'With our list of approved translators, we know who is doing the work.

If you use an agency, you rely on it for quality control, and our experience of that has not always been positive.' Denton Hall chooses to keep quality control in-house.

Mr Hancock says the firm is now instituting procedures for reporting back on the work of the approved translators to ensure that incidences of below-standard work can be weeded out.Mr O'Connor, who runs Legal Mind, a specialist translation agency in Tonbridge, says he makes basic checks.

'Good legal translation into English requires an adequate knowledge of foreign law as well as of English legal parlance,' he says.

It is also possible to judge a translation by 'the fluency of the English' and by spotting inconsistencies in the translation, he says.

If mistakes do emerge, it is hard to sue a translator because judgements about the quality of a translation are subjective.

However, the ITI does offer an arbitration service for aggrieved clients.

The advice from the translation industry is that as with other professional services, a buying decision must rest mainly on the quality of the individuals providing the service.