“The laws and Constitution are designed to survive, and remain in force, in extraordinary times,” wrote Justice Anthony Kennedy in the majority ruling on Boumediene v Bush, last Thursday’s landmark Supreme Court victory, extending habeas corpus rights to prisoners at Guantanamo Bay.

Issued towards the end of the week, and briefly overshadowed by reports of the sudden death of popular journalist and Meet The Press anchor Tim Russert, the significance of the judgment did not immediately sink in. Even John McCain’s first comment was somewhat muted “it obviously concerns me … These are unlawful combatants; they’re not American citizens.”

By Friday, the importance of the judgment was beginning to dawn on candidates and pundits alike. For Barack Obama it was “a return to the rule of law”, while for the right-leaning National Review it was “an intellectual, jurisprudential, and moral disgrace”. All of a sudden it seemed obvious that Kennedy’s words would become one of those classic quotes “shouting Fire in a crowded theatre”/”the Constitution is not a suicide pact” which define American ideas of government.

By 5-4, the Court ruled on two key issues: whether the appeal process put in place for the ‘enemy combatants’ was sufficient to act as a substitute for habeas corpus rights, and whether Guantanamo Bay constituted territory to which Constitutional rights could be extended. By saying no to the first proposition and yes to the second, they have effectively thrown the Bush administration’s detention strategy into chaos.

In establishing Guantanamo, the Bush administration relied on the 1950 Eisentrager judgement, which established that US occupied zones – in that case post-WW2 Germany — did not constitute US territory to which rights need be extended.

When habeas corpus applications filed on behalf of prisoners were granted in Rasul v Bush 2004, the Republican-controlled congress responded with a series of laws, the most recent of which was the 2006 Military Commissions Act, attempting to explicitly limit the court’s powers in Guantanamo. It is these provisions the court has overturned, finding that there would be ‘considerable risk of error’ by the military tribunals as to who is and isn’t a genuine military combatant.

The ruling will impact Guantanamo cases in different ways. There are currently 19 military commission trials under way, which the Bush administration has said will continue. However, lawyers for the defendants appear certain to try and halt these trials, by using the decision to seek a wider range of constitutional protections for their clients, thus making the current military commissions unworkable.

The other 200 of the 270 remaining detainees all have habeas corpus petitions outstanding. These will be reactivated, forcing the government to either release prisoners without comment, or reveal evidence about their alleged terrorist activities in open court.

The circumstances of Lakhdar Boumediene, the prisoner on whose case the decision was based, is an example of how wide the Guantanamo net was cast. Algerian-born Boumediene was arrested in Bosnia where he had taken citizenship and was charged with plotting to blow up the US embassy in the wake of 9/11. Acquitted by the Bosnian Supreme Court, he and five others (the ‘Algerian six’) were immediately abducted by US forces and taken to Guantanamo.

The government will now be in the embarrassing position of either releasing them unilaterally, or putting such evidence as it has before the open court. That evidence includes accusations that one member taught karate to Bosnian orphans, that another has a ring “similar in style to one popular with Hamas”.

Despite Guantanamo being full of cases of this sort, four justices dissented, the most vociferous opinion coming from Justice Scalia, who began his dissenting opinion stating that “the country is at war” and that the ruling would “certainly result in the death of American civilians”.

That cry has been taken up across the right, and by Friday John McCain had clearly decided it would be a rallying point for his campaign, adding to his more cautious earlier comments by telling a New Jersey town hall meeting that the decision was ”one of the worst … in the History of This Country.”

The Wall Street Journal called Kennedy’s majority opinion ‘plainly dishonest’, while on CBS, Newt Gingrich seemed to suggest that the President should simply ignore it: “This court decision is a disaster, which could cost us a city. And the debate ought to be about whether you’re prepared to lose an American city on behalf of five lawyers — it was a five to four decision.”

Will this developing campaigning play well for the GOP? It seems unlikely. A 2006 poll found that 60% of Americans believed that the Guantanamo Bay inmates were entitled to full legal rights. Most likely that number has increased in the last two years, as the ‘war on terror’ has shifted further from people’s minds, and domestic matters come to the fore.

Even news that a former Guantanamo detainee released by the military, Abdullah al-Ajmi, had blown himself up in Mosul last month has failed to excite much interest. Of course this may be due to the fact that authorities are reluctant to play Al-Ajmi’s martyrdom videotape on the air, as much of it is concerned with the conditions at Guantanamo Bay.

The positions taken up on the Boumediene decision have been predictable, but none have really got to the nub of the issue – that the decision does not extend habeas corpus rights to any prisoner of American forces anywhere. It relies both on the enduring possession of Guantanamo Bay, as something more than a short-term occupation, and the inadequacy of the substitutes supplied by the President and Congress.

This is one reason why McCain, after pausing for thought, came out swinging on the issue. For the 2006 Military Commissions Act was one that he brokered through Congress, and is very much attached to him. Insofar as the American people have any great interest in this at all, it would be easy for Obama to turn the issue around, further tying Bush and McCain together in the public mind.

However, he is unlikely to do that. Speaking Sunday – Father’s Day in the US – at Chicago’s southside Apostolic Church of God, Obama turned to the theme of absent black fathers, the importance of responsibility, the transmission of values and the teaching of empathy – “not sympathy” – empathy, the “ability to stand in someone else’s shoes”.

It was another great speech, one which is already resonating across the country, amongst white as much as black, and connecting with people where they live in increasingly uncertain times.

The week will undoubtedly go down in history as that of Boumediene vs Bush, according to one constitutional law expert, as important a ruling on the separation of powers as the Supreme Court has ever issued.

But the manner in which Obama’s speech is eclipsing it across the wires, even as we speak, is a measure of how different this campaign is becoming, and of how the Republicans are failing to respond to changed circumstances.