The breakdown of a marriage or similar relationship is traumatic - but that trauma can be increased by the experience of legally sorting out what is left over from the relationship. Few people know what to expect when entering this process.

Apart from the emotional debris of marriage breakdown, what needs sorting out is the custody of the children, the division of property and other trappings of a shared financial life. This is where the law intervenes. The couple may obtain a legal separation or, when they have lived apart for four years, a divorce. A legal separation can either be agreed - or obtained in court, where the terms are set by a judge. A divorce must always be finalised by a court. However, the main elements of its terms can be agreed in advance, and the judge will then formally grant the decree.

It is only when the couple cannot agree on the terms of their separation that the issues are decided by the court. Because family law cases are heard in camera, clients don't know what, if any, are the usual orders in relation to maintenance, to what becomes of the family home, or to the custody of children. These vary widely from court to court and from judge to judge.

Most separation and divorce applications are heard in the Circuit Courts. In Dublin, there are two Circuit Court judges who hear family law applications all the time. Outside Dublin, the judges have to hear other cases as well, and their interest in, and attitude to, family law matters may vary.

The only compass the lay person has in this situation is an experienced family lawyer, who has been before the particular judge many times. "Practitioners who do a lot of family law get a feel of what a judge will do in a particular case," says David Bergin, a Dublin solicitor and member of the Law Society's family law committee. "It is very difficult for solicitors who don't do a lot of family law.

"There is consistency in the Dublin Circuit Court, because the same two judges have been doing it for a long time. Outside of Dublin, you ask other practitioners who are used to that court about the attitude to selling the family home, for example. The circumstances in which that would be ordered would differ between Dublin and around the country."

He points out that variation among judges is equally true of any case that ends up in court. Individual judges will always bring their particular attitudes to bear on cases. But this is of little comfort to people who are probably facing the greatest disruption of their life in a family law dispute.

"The reliefs are discretionary," Muriel Walls, another Dublin solicitor, says. "So every judge brings his or her own views to bear. They do have meetings among themselves and have lectures on it. Still, the rule is - know your judge.

"Knowledge of how the case would be determined in court allows you to make other decisions - like settling at an early stage or going to the High Court. I have a system where I say to the client: `what do you think is fair?' If a woman wants everything and to have him in a bedsit, I say, `that won't happen'. Similarly, if the man says he doesn't want to pay maintenance."

Walls stresses that the "reliefs" spelt out in legislation apply to married couples. Unmarried partners have very little legal protection if the relationship breaks down.

Marie Baker, a Cork-based barrister, says: "You would have a fairly good idea what to expect. But there is great variety from Circuit to Circuit. Under the legislation, so many factors can be taken into account. Some Circuits act on a rule of thumb in relation to the family assets, and it can be predicted. This provides a framework within which you work, and a very high proportion of cases are settled as a result.

"There is an anecdote that there is a Circuit judge who treats each child as half a person. So if there are two children the wife and children get two-thirds, if there are four, the assets are divided in four, and she and the children get three-quarters. It is very rough justice.

"If there are very small children, it is unlikely any judge would sell the house. If the children are grown up, most judges treat the couple as equal. In the High Court, it is not so predictable."

Cases go to the High Court if there is a lot of money involved. One party can seek to have the case heard in the High Court, as it is likely to be heard more quickly, though it is much more expensive. Another reason for going to the High Court is if one party thinks the Circuit Court judge is likely to give them a less favourable judgment.

If there is a lot of money involved, the case can become more complex, especially if the couple has been a business partnership as well, or if one spouse has made considerable sacrifices which allowed the other to prosper in business. "If there is an enormous amount of money involved, there can be no assumption it will be 50-50," says Baker. "In some cases, it is as much about business equity as family equity."

The issue of the custody of children can be one of the most difficult, though attitudes here are changing. "Most family lawyers put the children first," says Bergin. "The Law Society publishes guidelines saying your priority must be the children, even to the detriment of your client. This means that if there is a report, say from a doctor, which is detrimental to your client, you have to disclose it.

"There is still a presumption in courts that a mother is a better parent in relation to young kids. But 10 years ago, a father would be laughed at if he looked for custody. He won't be now. I remember about 10 years ago going into the District Court with a father looking for custody for very good reason and the judge laughed. Then we had to get the health board involved and the children were taken into care.

"There are cases where the father gets custody, and fathers look for custody to a greater degree now. But there has not been a dramatic increase in the number of fathers looking for custody. I know of very few cases fought out on this issue. It is still not uncommon for the father to be the sole breadwinner.

"Some judges don't use the word custody or access at all. They talk about `arrangements for the children'. It is still hard to shift them away from the idea that young children are better off with the mother."

In Cork, legal practitioners operate on the basis that joint custody is best, according to Baker. This also means joint responsibility. She adds: "But it's a lottery in any court".