The courts have been a powerful agent of social change in the United States, but they can't change things on their own, according to veteran civil rights lawyer George Barrett.
"The courts can't rule in a vacuum, they rule in a context," he said. "You have to build a consensus. In relation to the civil rights movement, the courts were so much further ahead than the legislature and the general populace, it was necessary to build a social movement."
In 1954, in the historic Brown v the Board case, segregation in public education was ruled unconstitutional, setting the agenda for the civil rights movement. But this ruling did not affect private services like shops, hotels and transport.
Mr Barrett, a Nashville-born Irish-American, recalls being president of the Nashville Council on Community Relations in 1962 when he was contacted by the State Department in Washington. It asked him to find accommodation for the President of Ghana who would be visiting the city. At the time hotels and other facilities were segregated in Tennessee, and the US government did not want to see a foreign head of state embarrassed by being turned away from a hotel.
"Segregation did not just involve public functions like education, but the right of entrepreneurs to run their businesses as they liked. There was a clash of property rights and civil rights.
"It was difficult for the legislature to address these issues because of the stranglehold of southern senators. So we had to try other routes, by mobilising public support."
The coalition of white and black civil rights lawyers and black religious and community leaders which made up the civil rights movement embarked on a campaign of voter registration and boycotts. The latter were particularly effective.
"Black people withdrew their custom from down-town businesses, and most of them operated on such small margins that the loss of 10 per cent of their custom was significant and they began to ask politicians to `do something', " he explained. This spurred the politicians into action, and the Civil Rights Act was passed in 1964.
Yet, surely the situation of black people in the US today is such that a large number of them live without any contact with the law except when they are on the receiving end of charges relating to drugs and crime? "You cannot remake society purely by laws," replied Mr Barrett. "All you can do is create a framework. Thirty years ago there were three black members of Congress, and now virtually every southern state has one, and some have two. So at least some avenues of power have been opened up to them. A lot of these problems have to be dealt with in an economic and social, rather than a legal, context."
While the courts were ahead of the legislature and society with regard to civil rights, the opposite was the case with labour law, he said. Throughout the 19th century the judicial system treated strikes as criminal conspiracies, and the limited rights recognised during the first World War were rowed back in the 1920s. It took the Depression of the 1930s to bring about change, when, with 25 per cent unemployment, the owners of giant utilities were begging the government to take over running the economy, and basic workers' rights were guaranteed by law.
The process whereby rights pass into everyday usage is complex, and constantly in a state of flux, according to Mr Barrett. "Congress passes the outline of the law and then there is a process to tease out what it means in a series of court decisions. If they get too far away from the intention of the law, Congress intervenes to restate the law.
"This gives the judiciary an extraordinary role in the administration and interpretation of the law."
One of the best examples of how law influenced social change was in relation to the sale of tobacco, he said. "Twenty-five years ago the Surgeon General issued a report saying tobacco was a possible source of cancer. There was a series of one-shot cases. They all failed. Then there was a series of class action law suits against all the tobacco companies, where state Attorneys General represented some of the `classes'.
"All the research, and the evidence given in the other cases, were consolidated, and a settlement was reached with the companies. Then Congress had to do something. The same thing is happening on breast implantation."
Mr Barrett is reluctant to comment on the lessons for Ireland, but stressed: "The judiciary can't solve these things on its own. The legislature has to address these issues. If it doesn't it undermines the rule of law, which is the glue that holds us together."