WITH TEN minutes to go, it seemed that Italy might just pull off the greatest upset in the history of Europe’s signature rugby tournament. Pre-match forecasts gave the continent’s perennial minnows barely a 1% chance of toppling mighty England before their meeting in the Six Nations on February 26th, and with good reason. The Azzurri had won just one match in the tournament since 2013, and had given up a massive 96 points in the opening two rounds of this year’s edition. Conversely, England had won their previous 16 fixtures in all competitions, and arrived on Sunday at Twickenham Stadium, their concrete fortress of a home stadium, fully expecting to continue that streak. Victory would leave them one match away from equalling a record of 18 consecutive wins, set last year by the greatest New Zealand team of all time.

In the end, the home side did prevail, scoring 19 unanswered points in the final ten minutes to triumph by 36 to 15. But they had been given quite a scare by the unfancied Italians—and in a way that they would never have expected. Throughout the match the Azzurri exposed a loophole in the laws of rugby that bamboozled the English players and their supporters, and which nearly earned them an astonishing upset. More importantly, their interpretation of the rules could significantly change the way the game is played, in a manner that is rarely seen in modern sport.

The Italians’ ingenuity was in their “rucking”—or rather, their lack of it. Rucks are the building blocks of a rugby match. They occur once a player is tackled to the floor, which happens about 200 times in an 80-minute game. With the tackler and the ball-carrier on the ground, players from both the defending and attacking side form an impromptu scrimmage over the ball to vie for possession of it. The attackers have a significant advantage, since the floored ball-carrier can present the ball to his arriving teammates. This allows one side to retain possession for multiple plays, giving the game continuity. The defenders must also wait behind their side of the ruck—the offside line is marked by the back foot of their hindmost rucking player—until the ball emerges, in which time the attackers can organise themselves. In this respect, a ruck is similar to a scrimmage in American football.

The laws of the game, which are maintained by World Rugby, the sport’s governing body, state that a ruck is formed by “one or more players from each team, who are on their feet, in physical contact, close around the ball on the ground”. But what happens if the defending team does not commit any players to compete for possession? Until Saturday, most fans would have considered such a question daft: try telling a squad of bloodthirsty rugby players to idly stand around and let their opponents hold onto the ball after each tackle. Yet that is precisely what the Italians did—and it caused chaos. Since no rucks were formed when an Englishman was wrestled to the ground, there was no offside line during those plays. Subsequently, Italian defenders were free to wander around to the English side of the tackle and wait for the ball to arrive, since all passes must go backwards (see video). The sport was turned completely on its head. At times, it was like watching a computer game with a glitch, or a bizarre version of American football in which the defensive end gets to stand next to the quarterback.

Twickenham erupted in anger and confusion. Fans howled at the referee, the unflappable Frenchman Romain Poite, as blue shirts encroached upon English territory. The players, who usually dare not question an official, were even more frustrated. “Can I just get some clarity on the ruck thing?”, pleaded James Haskell, who has been playing international rugby for ten years. “I am a referee, not a coach”, replied Mr Poite, in a one-liner for the ages. In fact, Mr Poite had been given prior warning of the Italians’ master plan. The Azzurri had used a pre-game discussion with the referee—which is standard practice and allows the official to explain his interpretation of the laws to each team—to check the legality of their tactics, revealed Conor O’Shea, their coach, in a post-game interview. Mr O’Shea also pointed out that the rucking loophole had been occasionally exploited by other teams, albeit in a haphazard manner. He mentioned an incident in a match last year between Australia and Ireland, in which a player miraculously found himself intercepting a ball in a seemingly offside position. The Chiefs, a club side from New Zealand, have deliberately employed the tactic on occasion, but with mixed results.

Italy’s persistent use of the law in an international match was both unprecedented and highly effective, preventing a usually ruthless English offence from finding any kind of momentum for 70 minutes. Jonny Wilkinson, a World-Cup-winning Englishman working as a television pundit for ITV, noted that it made rugby suddenly resemble netball, in which players have to nimbly pass the ball over and around opponents. Eddie Jones, England’s famously forthright coach, congratulated the Italians for their intelligent tactics while also claiming that it ruined the game: “That’s not rugby today. People don’t pay money to see that.” Mr Jones also suggested that World Rugby should consider changing the law.

That might happen eventually—but not before the final two rounds of the Six Nations, according to Robert Burns of RugbyRefs.com, a blog and forum for referees. Mr Burns explains that World Rugby would never make alterations during a season, and that any proposed changes must be trialled at lower levels to assess their impact. (We have asked World Rugby about this, and are awaiting their comment.) Mr Burns also believes that there is little reason to legislate against Italy’s inventiveness. Such outside-the-box tactics have been tried before in the abridged seven-a-side version of the sport, and at line-outs—in which the ball is thrown back into play from the sideline—without drastically affecting the flow of the game. England eventually found a way to cope with the unusual strategy, by finding gaps around the tackle area that might not have occurred in a conventional ruck defence. Still, it is easy to see how a better-drilled side than Italy could use this strategy to effectively obstruct any pass from contact.

Should World Rugby outlaw the practice? Those in favour of a ban will cite two famous cricketing precedents. The first is the “Bodyline” series of 1932-33 between England and Australia, in which the English positioned several fielders close to the Australian batsmen while bowling at their head and ribs, in the hope of inducing a fended catch. The tactics made traditional stroke-play almost impossible and led to several injuries. The Marylebone Cricket Club (MCC), which administers the laws of the game, subsequently limited the number of close fielders and head-height balls that are allowed. The Australians were culpable in the second incident (one which Mr Jones, an Australian himself, recalled after Sunday’s game). In 1981 Trevor Chappell rolled the final ball of a match against New Zealand along the ground, which made it impossible for the batsman to hit it aerially into the stand for the six runs needed to draw the game. Underarm bowling was soon banned, but not before New Zealand’s prime minister, Robert Muldoon, had decried “the most disgusting incident I can recall in the history of cricket”.

In both cases, the MCC decided that the tactics were against the “spirit” of the laws: a somewhat nebulous concept which is defined in a preamble to the rulebook as a combination of “fair play” and “respect for… the game’s traditional values”. The laws of rugby also have a chapter about the principles of the game, which mentions the “balance of contestability and continuity”. World Rugby will have to decide whether encroaching defenders make for too much disruption and too little momentum.

Rugby purists will be outraged if the loophole remains open. But perhaps they should be open-minded. Nineteenth-century footballers scoffed when “hacking” (the indiscriminate kicking of an opponent) was outlawed and when passing replaced dribbling as the primary means of propelling the ball upfield. And rugby lore holds that the sport itself was invented when William Webb Ellis, a pupil at Rugby School in Warwickshire, defied the rules of football and ran with the ball in his hands. The rulebook remarks: “that the game should have its origins in an act of spirited defiance is somehow appropriate.” Webb Ellis, were he alive today, would doubtless have enjoyed Italy’s dogged act of rebellion.

Correction (February 27th): A previous version of this article suggested that Italy invented the tactic of refusing to commit players to a ruck. A fan of the Chiefs, a club side from New Zealand, has pointed out that they have used this strategy occasionally in the past. The names of the offending bowler and the outraged politician in the 1981 cricketing debacle have also been corrected.