The Act changed existing criteria for a successful claim, by requiring claimants to show actual or probable serious harm (which, in the case of for-profit bodies, is restricted to serious financial loss), before suing for defamation in England or Wales, setting limits on geographical relevance, removing the previous presumption in favour of a trial by jury, and curtailing sharply the scope for claims of continuing defamation (in which republication or continued visibility constitutes ongoing renewed defamation).

Such cases are referred through a Defamation Recognition Commission (DRC) to a new Independent Regulatory Board (IRB), to provide arbitration services.

[7][citation needed] At the behest of Finance Minister Sammy Wilson, the Northern Ireland Assembly refused to approve the new Defamation Act, meaning the old UK laws still apply there.

[8] Proponents of the law and Irish authors have warned that Belfast might replace London as the new capital for "libel tourism".

[9] Additionally, there are worries that UK newspapers would either need to end Northern Ireland editions, or else be forced to comply by the old guidelines in their stories.