The murder of Drummer Lee Rigby, on a south-east London street in daylight last week, has reignited the debate in Britain about national security legislation. Some Tory and Labour MPs want to reintroduce the Communications Data Bill which was recently junked following opposition from Nick Clegg, the leader of the Liberal Democrats (which forms part of Conservative David Cameron's coalition government).
Clegg and his colleague Simon Hughes went along with the criticism that the communications data legislation which was being proposed by Prime Minister Cameron amounted to a ''snooper's charter''. However, on Sunday, Home Secretary Theresa May said British police and intelligence services needed access to communications data to monitor the contacts of terrorism suspects. She was supported by Labour's Alan Johnson and Lord Carlile, a Liberal Democrat peer.

The Rigby murder has still to be fully investigated. Yet there seems to be overwhelming evidence that this was an act of Islamist terrorism designed to intimidate Britain in particular and Western democracies in general. One of the murderers is said to have told a bystander: ''You will never be safe.'' While hacking the soldier to death, the assailants were heard to call out ''Allahu Akbar'' meaning ''God (Allah) is the greatest''.

The Islamist suicide/homicide attacks on London commuters in 2005 and the murder near the Woolwich army barracks were carried out by Britons of Muslim faith. The combined effect of both attacks will make life difficult for the overwhelming majority of law-abiding British Muslims. Also, the Rigby murder is likely to lead to growing opposition to immigration.

In view of this, it would make sense for the Liberal Democrats and the Labour Opposition, led by Ed Miliband, to support whatever legislation Cameron and May regard as necessary to enhance national security. Even if the communications data legislation is a snooper's charter, it will not lead to the death of anyone nor will it undermine social harmony in British society. Since some terrorists have effectively declared war on Britain, it stands to reason that the democratically elected government will resort to war-time security.

On May 14, shortly after the mass murder at the Boston Marathon perpetrated by two Chechnya-born Islamists and not long before the London outrage, Australia's federal Attorney-General, Mark Dreyfus, released two findings on national security legislation. The first was the annual report of the Independent National Security Legislation Monitor, headed by Bret Walker, SC. The second, the Council of Australian Governments Review of Counter-Terrorism, headed by Anthony Whealy, QC.

The Walker report made recommendations about the Commonwealth's security legislation with respect to control orders, preventative detention, ASIO's powers and the definition of a terrorist act. The Whealy report examined the counter-terrorism laws which were enacted by Commonwealth, state and territory governments in late 2005 and which were supported by Coalition and Labor.

Both Walker and Whealy recommend narrowing the definition of terrorism and advocate the repeal of preventative detention without charge for a designated crime. Walker also advocated the cessation of control orders concerning individuals suspected of being likely to commit a terrorist act.

When Dreyfus released the reports he did so without enthusiasm, making reference to the terrorist attack in Boston. This approach made sense then. It makes even more sense two weeks later, following the London murder. The Attorney-General drew attention to the fact that ''under Australia's counter-terrorism framework, four major terrorist attacks on Australian soil have been disrupted'' by police and intelligence services in recent years.

As Prime Minister Julia Gillard pointed out in January, ''23 convictions have resulted from prosecution'' of individuals who planned terrorist attacks in Sydney and Melbourne. In other words, instances similar to those which took place in London and Boston could have occurred in Australia.

Opposition to the national security legislation – which is supported by Labor and the Coalition, but not the Greens – also has a bipartisan base, of sorts. The civil liberties left have described the existing legislation as, variously, ''ridiculous'' (Rob Stary), ''a knee-jerk reaction'' (Stephen Blanks) and ''a product of hysteria'' (Jessie Blackbourn and Nicola McGarrity).

Then there is the libertarian right, as embodied in the position adopted by some staff at the Melbourne-based Institute of Public Affairs. For example, Christopher Berg wrote on the ABC's The Drum website on August 14, 2012, that the national security legislation passed by the Howard, Rudd and Gillard governments ''has damaged our legal system''.

The position of the civil liberties left and the libertarian right invariably looks less plausible after each terrorist attack.

Gerard Henderson is executive director of The Sydney Institute.