The Washington Post reports that in a decision handed down last week by the US Supreme Court, members of the controversial Kansas-based Westboro Baptist Church, who routinely conduct anti-gay protests at military funerals, were protected by the First Amendment.

The almost unanimous decision is seen as a powerful demonstration of the nation's tolerance of even the most hateful public speech.

Members of Westboro are notorious for picketing military funerals with signs reading Thank God for Dead Soldiers and Fags Doom Nations. Church members believe that wars, and natural disasters, are divine punishment because the United States tolerates gays.

The church is led by patriarch Fred Phelps, who has 13 children and 54 grandchildren, many of whom are church members.

The decision has been described by commentators as writing a new chapter in the court's findings that freedom of speech is so integral to the nation that it even protects cruel and unpopular protests.

Chief Justice John G Roberts Jr. wrote that while the Westboro Baptist Church's picketing at fallen soldiers' funerals was "certainly hurtful and its contribution to public discourse may be negligible", the reaction may not be "punishing the speaker".

"As a nation we have chosen a different course - to protect even hurtful speech on public issues to ensure that we do not stifle public debate," Roberts said.

Central to the case was a protest in 2006 at the funeral of 20-year-old Marine Lance Corporal Matthew Snyder who was killed in Iraq. Snyder's funeral was one of more than 600 funerals the church has picketed. Snyder's father, Albert, filed a lawsuit seeking damages on the basis that the group had turned the solemn occasion into a "circus".

Margie Phelps, the daughter of Westboro's founder and the lawyer who argued the case before the court, labelled the decision a providential ruling that was more than she could have hoped for.

"We're going to picket more," she said.

The court's lone dissenter was Justice Samuel A. Alito Jr., who said the First Amendment does not include the right to "brutalise" people.

"Our profound national commitment to free and open debate is not a license for the vicious verbal assault that occurred in this case," he wrote.