WASHINGTON DC, United States?The US Senate on Monday passed a bill to shield US journalists, authors, and publishers from "libel tourists" who file suit in countries where they expect to get the most favorable ruling.

The popular legislation headed to the House of Representatives, which was expected to approve it and send the measure to US President Barack Obama to sign into law despite misgivings from key US allies.

Backers of the bill have cited England, Brazil, Australia, Indonesia, and Singapore as places where weak libel safeguards attract lawsuits that unfairly harm US journalists, writers, and publishers.

The Senate approved the measure in a "unanimous consent" voice vote.

The bill's supporters have said that "libel tourism" undermines free speech rights under the US Constitution's cherished first amendment, and so erode accountability of powerful figures in a healthy democracy.

The measure would prevent US federal courts from recognizing or enforcing a foreign judgment for defamation that is inconsistent with the first amendment of the US Constitution, which guarantees freedom of speech.

It would bar foreign parties in such cases from targeting the US assets of an American author, journalist, or publisher as part of any damages.

Senate Judiciary Committee chairman Patrick Leahy, a Democrat, charged that libel judgments in foreign courts were "undermining" freedom of speech and of the press and "chilling" open debate in the United States.

"While we cannot legislate changes to foreign law that are chilling protected speech in our country, we can ensure that our courts do not become a tool to uphold foreign libel judgments that undermine American First Amendment or due process rights," he said in a statement.

The US Constitution's first amendment, backed by a series of US Supreme Court decisions, makes it harder to win a libel suit in the United States relative to many other countries.

"This bill is a needed first step to ensure that weak free-speech protections and abusive legal practices in foreign countries do not prevent Americans from fully exercising their constitutional right to speak and debate freely," said Senator Jeff Sessions, the top Republican on Leahy's committee.