It is a rare achievement these days for the Senate to pass anything of real substance by a unanimous vote. But an important bill that protects Americans from the whims of foreign libel judgments was passed earlier this week by unanimous consent. Once it passes the House and is signed into law, it will provide a safeguard to authors and publishers threatened with ruinous foreign judgments.

In the United States, a plaintiff alleging libel must prove that a statement is false and defamatory, and public figures have to show that a writer acted with actual malice in making a false statement. But these protections, rooted in the First Amendment, do not exist in places like Britain, Australia and Singapore, where the burden is often on the author, once accused of libel, to show that a statement is true.

To sidestep American protections, subjects of books have sued publishers and authors in British courts where they have a better chance of winning. The practice, known as libel tourism, counts on a system in which American courts will enforce British fines and penalties.

The bill passed by the Senate on Monday would prohibit American courts from enforcing foreign defamation judgments if the judgments are inconsistent with First Amendment protections. In other words, if a British court finds that an American author has committed libel but has not conducted the trial with the same legal standards as an American court, the judgment against the author would be void in the United States. Americans who are found overseas to have committed libel can also sue in federal court to have that judgment found to be ﾓrepugnant to the Constitutionﾔ or American law.

These kinds of cases have come up far too often. One of the best known examples was that of Rachel Ehrenfeld, who wrote a 2003 book called ﾓFunding Evil: How Terrorism Is Financed ﾗ and How to Stop It,ﾔ that accused a Saudi businessman, Khalid bin Mahfouz, of providing financial support to Al Qaeda before the Sept. 11, 2001, attacks. After Mr. Mahfouz sued for libel in Britain ﾗ a charge that Ms. Ehrenfeld refused to defend ﾗ a British judge ordered her to pay ﾣ10,000 each to Mr. Mahfouz and his two sons, and more than ﾣ100,000 in legal costs, a total equaling about $230,000 at the time. She refused to pay, and the case led the New York State Legislature to pass a bill similar to the Speech Act in 2008.

The House has already passed a similar bill and is expected shortly to support the version approved by the Senate, giving authors in the rest of the country the same protections that exist in New York. The next step is for the new British government to take the hint and follow through on the promise it made earlier this month to review and overhaul its libel laws. No one in either country wins if writers cannot express themselves freely.