Almost ten years after 9/11, in May of this year, a majority of the US House of Representatives voted to give President Obama – and all future presidents – more war authority than Congress gave to President Bush two days after the 9/11 attacks: a president would no longer have to show a connection to 9/11, or even any specific threat to America, before using military force anywhere in the world that a terrorism suspect may be found, including within the United States.

The House vote sought to place the nation on a permanent war footing at a time when responsible policy-making called for the opposite. Osama bin Laden had been killed days before the vote. As Defence Secretary Leon Panetta would soon confirm, we were "within reach of strategically defeating al-Qaida". The Obama administration had threatened to veto the bill, telling the House that the executive branch already had all the war powers it needed. And America is exhausted by the high cost in blood and treasure of two wars begun with the stated goal of combating terrorism. Yet, instead of pausing to consider whether the time had come to ratchet down the nation's war against terrorism, the House voted to expand it. If the House bill is approved by the full Congress (so far, the Senate has not gone along with the House), it would be the single largest handover of unchecked war power to the executive branch in American history.

Why would so many in the House be so willing to give such vast and undefined war powers to the executive?

The answer lies in the unrelenting drumbeat by some of our political leaders to force America into a military response to any act or even threat of terrorism anywhere in the world, including far from any actual battlefield. But it is not only some in Congress who have embraced a worldwide war against terrorism. Since 9/11, both the Bush and Obama administrations have contended that the United States is engaged in a global armed conflict against loosely defined terrorist entities and undefined "associated forces". The most concrete policies that have followed are the indefinite military detention and lethal targeting of civilians far from any conventional theatre of war.

Guantánamo Bay, which from its inception was a laboratory for unlawful military interrogation, detention and trials, remains an enduring symbol of indefinite military detention. And President Obama's pledge to close Guantánamo on his second day in office has been undermined by his own subsequent announcement of a policy enshrining at Guantánamo the principle of indefinite military detention without charge or trial.

Indefinite detention is unnecessary: federal "material support" statutes allow the government to secure convictions without having to show that any specific act of terrorism has taken place, or is being planned, or even that a defendant intended to further terrorism. If the government does not have evidence that a person meets even these minimal standards, it is hard to imagine any possible justification for indefinitely detaining that person.

But the real danger of the Guantánamo indefinite detention principle is that its underlying rationale has no definable limits. Military detention may be legitimate for those captured on an actual battlefield, as our supreme court recognised in Hamdi v Rumsfeld. But in the context of a war against terrorism without specified enemies and geographic or temporal limitations, it is simply not possible, let alone lawful, for us to detain indefinitely everyone who we suppose may, at some point, present a danger.

Targeted killing poses an even graver threat to human rights and the international rule of law because the government claims the unchecked authority to impose an extrajudicial death sentence on people located far from any battlefield. In an actual war, the government's use of lethal force may be lawful, of course, but outside that context, the intentional killing of a civilian without prior judicial process is illegal, except in the narrowest and most extraordinary circumstances – as a last resort to prevent concrete, specific and imminent threats that are likely to cause death or serious physical injury.

Under the targeted killing programme begun by the Bush administration and vastly expanded by the Obama administration, the government now compiles secret "kill lists" of people who remain on those lists for months at a time – and so, by definition, cannot always pose "imminent" threats. And it has refused to disclose the legal criteria it uses to make its targeted killing decisions. There is no way for the American public or the world to know whether the targeted killing programme is lawful, let alone whether the people our government kills truly present an imminent threat to our nation. We do know, though, that in the decade since 9/11, the government has repeatedly labelled people as terrorists – including at Guantánamo – only for us to find out later, or for a court to find, that the government's evidence was exaggerated, wrong, or nonexistent.

In the last ten years, America has become an international legal outlier in invoking the right to use lethal force and indefinite detention against suspected terrorists outside battle zones. If we further entrench the militarisation of our counter-terrorism efforts, our nation risks becoming a legal pariah, to the detriment of those efforts. Abiding by their own international and domestic law obligations, key allies have rightly refused to extradite suspected terrorists to the United States for military detention or military prosecution, requiring assurances that prosecution will take place only in our criminal justice system.

In the name of national security, our leaders are also undermining our more enduring security: the international legal framework that protects our long-term interests. Political leaders who insist that the laws of war permit our executive to treat as a battlefield any location where a terrorism suspect is found are giving a green light to other nations – including those with less respect for international legal institutions – to do the same.

For Congress and our executive branch to commit us to an "everywhere and forever" war undermines values that define us in our own eyes and in the eyes of the world, and it sends the dangerous message that we are willing to give terrorists what they seek – the status of military warriors, not common criminals. Such a global war approach to counter-terrorism does not make us safer. It is not too late to chart a different course, but the American people, and our political leaders, now need to show the courage, and the will, to do so.