Liberal Democrat peers made a final attempt this week to derail new measures to change the law on universal jurisdiction. Under the present system, magistrates can issue arrest warrants to foreign politicians and military figures accused of war crimes.

A private application brought by pro-Palestinian activists led to a warrant being issued for Israeli Opposition leader Tzipi Livni in December 2009. Ms Livni served as foreign minister in the Israeli government during Operation Cast Lead in Gaza.

Under proposals in the new Police Reform and Social Responsibility Bill, the consent of the Director of Public Prosecutions will be necessary before any such arrest warrant is issued. The bill reached report stage in the House of Lords this week, which allowed opponents of the law change to table final amendments.

Lord Macdonald, the former DPP, anti-Israel campaigner Baroness Tonge and fellow Liberal Democrat peer Lord Thomas of Gresford proposed an amendment to limit the ability of the DPP to use his discretion in a war crimes case. Instead, an obligation would be placed on him to give his consent "if the evidence establishes a realistic prospect of conviction and the prosecution would be in the public interest".

Under the amendment the DPP would also be obliged to grant the application if there was a reasonable suspicion that an offence had been committed and that further investigation of the case could provide further evidence to lead to a conviction.

Despite the last-ditch efforts to water down the new provisions, it now looks likely the change to the law on universal jurisdiction will finally go ahead. The JC understands that Liberal Democrat peer Lord Carlile has played a crucial role in rallying support in the Lords for the change. Lord Goldsmith, the former Labour Attorney General, has also proved to be a key figure in persuading fellow peers that the law needs to be changed.