One significant difference with respect to US and British libel laws is that the US bases its decisions with respect to libel on whether or not the court is upholding the First Amendment, while Britain is more concerned with addressing harm from slander. While Britain has made some legal decisions to uphold free speech, doing so is not Britain's primary concern because Britain does not have a First Amendment.
Since the US acts to uphold the First Amendment granting the freedom of press and speech, the U.S. Supreme court draws a clear distinction between public figures suing for libel concerning public affairs and private individuals suing for libel over private affairs. The court case New York Times Co. vs. Sullivan was the first Supreme Court case to set a precedent with respect to public figures suing for liable. The First Amendment protects the freedom to speak out about all matters of public interest; therefore, the Court ruled that, in cases concerning public issues, the plaintiff must prove that the defendant intentionally made remarks that were untruthful and damaging. We refer to a person's intention to harm or damage the reputation of another person as malice ("Libel"). In other words, with the intention of upholding the freedoms of speech guaranteed by the First Amendment, the Court ruled public figures will not need to be compensated for statements concerning public matters that slander their characters if the public figures cannot prove the statements were made with malicious intent.
When it comes to libel cases concerning the slander of private individuals with respect to public affairs, the Supreme Court has ruled that slanderous statements are not supported under the First Amendment and private individuals can be compensated for any damages caused by slander. But, again, the plaintiff must be able to prove that the slanderous statements were made about the private individual, concerning a public affair, with the intention of malice. One example of such a court case is Gertz v. Robert Welch, Inc ("Libel").
Only in cases about private matters will private individuals be able to sue for libel if it cannot be proven that the plaintiff acted out of malice. In Dun & Bradstreet, Inc. vs. Greenmoss Builders, Inc, the Supreme Court ruled that the defendant needed to pay for damages, even though the slanderous statements were not made maliciously ("Libel").
In contrast, in Britain, English law allows any individual, public or private, to sue if any published statements are made that "defame" the person, regardless of whether or not those statements were made with malicious intent or not. A defaming statement can even be implied; for example, a photograph can portray a politician as being corrupt, and that politician can sue for libel ("English Defamation Law").
The most important difference between US and British libel law to note is that, in the US, the burden of proof lies with the plaintiff, while in Britain, the burden of proof lies with the defendant. Under English law, any individual can come to court claiming that a published statement is defaming. It is then the responsibility of the defendant to prove that the published statement is actually true because any defaming statement is believed to be false until proven true. In the US, the defaming statement is believed to be true until otherwise proven false. Under English law, the defendants can prove a defaming statement is true by proving that the statement is at least fair, meaning a statement any "reasonable person could have held"; defendants can also argue their case based on the grounds of if the statement was made with public interest in mind ("English Defamation Law").