By Eugene Robinson.

WASHINGTON — In retrospect, George W. Bush’s legacy doesn’t look as bad as it did when he left office. It looks worse.

I join the nation in congratulating Bush on the opening of his presidential library in Dallas. Like many people, I find it much easier to honor, respect and even like the man — now that he’s no longer in the White House.

But anyone tempted to get sentimental should remember the actual record of the man who called himself The Decider. Begin with the indelible stain that one of his worst decisions left on our country’s honor: torture.

Hiding behind the euphemism “enhanced interrogation techniques,” Bush made torture official U.S. policy. Just about every objective observer has agreed with this stark conclusion. The most recent assessment came earlier this month in a 576-page report from a task force of the bipartisan Constitution Project, which states that “it is indisputable that the United States engaged in the practice of torture.”

We knew about the torture before Bush left office — at least, we knew about the waterboarding of three “high-value” detainees involved in planning the 9/11 attacks. But the Constitution Project task force — which included such respected eminences as Asa Hutchinson, who served in high-ranking posts in the Bush administration, and William Sessions, who was FBI director under three presidents — concluded that other forms of torture were used “in many instances” in a manner that was “directly counter to values of the Constitution and our nation.”

Bush administration apologists argue that even waterboarding does not necessarily constitute torture and that other coercive — and excruciatingly painful — interrogation methods, such as putting subjects in “stress positions” or exposing them to extreme temperatures, certainly do not. The Constitution Project task force strongly disagrees, citing U.S. laws and court rulings, international treaties and common decency.

The Senate intelligence committee has produced, but refuses to make public, a 6,000-page report on the CIA’s use of torture and the network of clandestine “black site” prisons the agency established under Bush.

One of President Obama’s worst decisions on taking office in 2009, in my view, was to decline to convene some kind of blue-ribbon “truth commission” panel that would bring all the abuses to light.

It may be years before all the facts are known. But the decision to commit torture looks ever more shameful with the passage of time.

Bush’s decision to invade and conquer Iraq also looks, in hindsight, like an even bigger strategic error.

Saddam Hussein’s purported weapons of mass destruction have yet to be found, of course; nearly 5,000 Americans — and untold Iraqis — sacrificed their lives to eliminate a threat that did not exist. We knew this, of course, when Obama took office. It’s one of the main reasons he was elected.

We knew, too, that Bush’s decision to turn to Iraq diverted focus and resources from Afghanistan. But I don’t think anyone fully grasped that giving the Taliban a long, healing respite would eventually make Afghanistan this country’s longest or second-longest war, depending on what date you choose as the beginning of hostilities in Vietnam.

And it’s clear that the Bush administration did not foresee how the Iraq experience would constrain future presidents in their use of military force. Syria is a good example. Like Saddam, Bashar al-Assad is a ruthless dictator who does not hesitate to massacre his own people. But unlike Saddam, Assad does have weapons of mass destruction. And unlike Saddam, Assad has alliances with the terrorist group Hezbollah and the nuclear-mad mullahs in Iran.

I do not advocate U.S. intervention, because I fear we might make things worse rather than better. But I wonder how I might feel — and what options Obama might have — if we had not squandered so much blood and treasure in Iraq.

Bush didn’t pay for his wars. The bills he racked up for military adventures, prescription-drug benefits, the bank bailout and other impulse purchases helped create the fiscal and financial crises he bequeathed to Obama. His profligacy also robbed the Republican Party establishment of small-government credibility, thus helping give birth to the tea party movement. Thanks a lot for that.

As I’ve written before, Bush did an enormous amount of good by making it possible for AIDS sufferers in Africa to receive antiretroviral drug therapy. This literally saved millions of lives, and should weigh heavily on one side of the scale when we assess The Decider’s presidency. But the pile on the other side just keeps getting bigger.