In 67 A.D., the Roman emperor Nero used 10 horses in an Olympic race featuring four-horse chariots. He tumbled, failed to finish and was still declared the victor. In the 1904 Summer Games, an American named Fred Lorz was the first runner to finish the marathon — aided by 10 miles spent in an automobile. In 1938, a German named Dora Ratjen set the women’s high jump record, which stood until officials learned she was actually a he. In more recent times, ballplayers juiced, cyclists lied, fighters took bribes, football teams spied and golfers fluffed lies.

So it shouldn’t be a surprise the New England Patriots advanced to this year’s Super Bowl having used footballs that were (allegedly) low on air pressure, making them easier to grip. As long as there have been rules, there have been rule-benders and rule-breakers. While rule books are printed in black and white, they regularly have been challenged, creatively interpreted and ignored entirely.

The line separating what’s acceptable from what’s illegal can be gray. Depending on whom you ask, the Patriots brazenly blurred that line, pushed it or obliterated it entirely, gamesmanship trumping sportsmanship.

As the controversy grows over how the Patriots came to use under-inflated footballs in their AFC championship victory over Indianapolis on Sunday, Coach Bill Belichick and quarterback Tom Brady held separate news conferences Thursday to deny knowing anything about it.

“When I came in Monday morning, I was shocked to learn of the news reports of the footballs,” Belichick said in the morning. “I had no knowledge whatsoever of this situation until Monday morning. I’ve learned a lot more about this process in the last three days than I knew or had talked about in the last 40 years coaching in this league.”

Post NFL editor Keith McMillan recruits a few coworkers to see if they can tell which football has been under-inflated by 2 PSI, the amount the NFL claims the New England Patriots' game balls were deflated. (Davin Coburn and Jason Aldag/The Washington Post)

Said Brady later in the day: “I have no knowledge of anything. I have no knowledge of any wrongdoing. I’m very comfortable saying that. I’m very comfortable saying that nobody did — as far as I know.”

Regardless of how the NFL resolves the matter, the episode — and whatever involvement the veteran coach and star quarterback had in it — has exposed the line between innovation and cheating for what it is: fluid.

“Think about it: There was a time we didn’t even have the forward pass,” said Shawn Klein, who teaches philosophy at Rockford (Ill.) University and runs the Web site “Someone had to push the boundaries [and] say, ‘Maybe this is the way it should be done.’ ”

Different sports, competitors and fan bases regard their respective rule books with varying degrees of sanctity. Former pitcher Gaylord Perry cracked jokes during his Hall of Fame induction speech about his well-known rule-breaking involving doctoring the baseball. Sluggers such as Barry Bonds and Mark McGwire, meanwhile, can’t get into Cooperstown without first purchasing a ticket at the door. The slam dunk was once illegal in college basketball and discouraged in the pros; today it’s a staple of the sport.

Evolving technology, too, requires constant rule changes in auto racing, golf and many extreme sports. In more traditional sports such as baseball, adopting instant replay is akin to relocating a mountain one shovelful at a time. The common thread is usually a level playing field and agreed-upon terms of play.

“I think people enjoy sports — and men in particular — because it gives order to the universe. Something is either fair or foul, either a strike or a ball,” said Randall Balmer, an author, historian and chair of the religion department at Dartmouth College, where he teaches a course on ethics in sport. “Nothing riles up a sports fan more than something that disrupts their orderly universe. It’s implicit in any athletic event that we are all going to play by the same rules, so any sort of transgression is taken pretty seriously by a lot of people.”

As history might suggest, Klein says cheating might very well be ingrained in the nature of competition. But it’s also a part of human nature. He points to a young child challenging a parent. An artist thinking outside the box. An activist challenging authority.

The Post Sports Live panel weighs in on how the NFL's investigation into whether the Patriots deflated footballs before their AFC championship game against the Colts affects the team's legacy. (Post Sports Live/The Washington Post)

“It’s people asking, how far can we go? Asking questions, why is the line here? Maybe the line should be somewhere else? Let’s push and see,” Klein said. “That can lead us to innovation and important change. . . . Rule-pushers — and to an extent the rule-breakers — they play an important role in sport but also in life and culture so that we can adapt and learn new things.”

Belichick’s pursuit is relatively modest — a fourth Super Bowl trophy — and part of his mid-career legacy already seems clear: a competitor who was willing to bend rules, even break them at times, to win. In 2007, long before anyone was worried about air pressure in footballs, he was busted for videotaping opposing coaches’ signals. But he’s also noted for creatively operating within the rules, most recently employing a unique offensive formation against Baltimore two weeks ago that had Ravens coaches and players mistakenly crying foul.

“Maybe those guys gotta study the rule book and figure it out,” Brady said at the time.

Against the Ravens, their bold strategy was lauded, not lambasted. They tiptoed up to the line but didn’t cross. This latest incident, though, leaves a football nation — or at least fans of 31 other teams — convinced the Patriots have no problem stepping well over that line, if necessary.

“The Patriots are habitual line-steppers,” Baltimore defensive end Chris Canty told NBC Sports this week.

But whether it’s deflated footballs or creative strategy, the same motivation propelled Belichick to approach the line in the first place: seeking any sort of advantage over a foe.

Cheating and challenging norms have been a part of sports for centuries. The Roman emperor flaunted rules and conventions and wore a crown of olive leaves. Today’s most polarizing NFL czar does the same, wearing a headset and a sleeveless hoodie instead.