It’s back. Torture has made its return as an issue being discussed by presidential candidates.

Donald J. Trump has dredged it from the has-been issue pile, saying something about how he would order the waterboarding of bad guys in order to get information from them.

Don’t do it, says someone who knows a thing or three about torture.

I prefer to stand with the expert on these things. That would be U.S. Sen. John McCain, R-Ariz., who lost the presidency in the 2008 campaign to fellow Sen. Barack Obama.

What’s a bit ironic, of course, is that McCain and Trump would be at loggerheads over this issue. Why the irony? You’ll recall that one of Trump’s initial insults was tossed in McCain’s direction when he said that the senator is a war hero only because he got captured by the North Vietnamese during the Vietnam War and that he (Trump) preferred people “who weren’t captured, OK?”

Here they are again. McCain has long opposed the use of waterboarding as an “enhanced interrogation” technique. He calls it torture, which he believes breaks faith with American principles.

What does McCain now about torture? More than most Americans ever will know, and certainly far more than Donald Trump knows about it.

McCain’s five-plus years as a captive after being shot down during the Vietnam War included many years of torture: beatings, solitary confinement and the communists’ various versions of “enhanced interrogation.”

When the senior senator from Arizona calls a particular act a form of torture, well, I am inclined to believe him.

I am doing so in this particular exchange.

He’s right as well to suggest that the information gleaned from waterboarding has been sketchy at best and has not provided nearly as much actionable intelligence as has been suggested.

Sen. McCain isn’t speaking as some soft-pedaling, squishy, politically correct liberal. He speaks as someone who’s been straight to hell and back.