Does anyone understand the offside law?

Deciding whether a player is offside used to be simple but, as Glenn Moore explains, Fifa's new edict on interfering with play makes controversy at the World Cup a virtual certainty

Back in the days of yore, when football was as sexy as Nora Batty, the offside law was the perfect way to expose a counterfeit football fan. Girlfriends, in particular, would be subjected to "the offside test". If they did not know that a player in the opposing half was offside if there were fewer than two defenders (including the goalkeeper) between him and the goal when the ball was played forward, except from a goal kick or throw-in, they really were only interested in looking at Gary Lineker's legs.

Now, however, the only people who understand Law 11 are referees and linesmen (most of them anyway) and people who should get out more often. Which is a problem, because if one aspect of this World Cup is as certain as David Beckham finding a camera to look at, it is that misunderstanding of the offside law will lead to controversy.

This, of course, would be entirely in keeping with the history of a law which dates back beyond the Crimean War and is much older than those banning hacking (kicking), handling and one-handed throw-ins.

It was in 1848 that the Cambridge Rules, the first serious attempt to codify the game as played by the public schools of England defined an offside player as anyone in front of the ball (a definition which still applies in rugby).

This was incorporated in the rules adopted by the newly formed Football Association in 1863. As a result most teams attacked en masse, as in rugby.

Three years later came the first significant change. Players were now onside if three opponents were between them and the goal. As a result teams evolved to play 2-3-5.

That law was brought into disrepute by Bill McCracken, of Newcastle United, prior to the First World War. The right-back was so adept at springing an offside trap he even provoked a pitch invasion by infuriated spectators.

With his tactics being copied, resulting in countless stoppages, the law was changed in 1925 reducing the required number of defenders from three to two. The impact was incredible. In the following Football League season there were 36 per cent more goals. Many goalscoring records date back to this period, including that of most League goals in a season, Dixie Dean's 60 for Everton in 1927-28.

Inevitably, the coaches struck back with Arsenal's Herbert Chapman to the fore. Together with his captain Charles Buchan he devised the "WM" formation, in which the centre-half withdrew to become the "stopper" centre-back, and the inside-forwards dropped deeper.

The offside law remained largely unchanged until the modern era, not least because only in England was it a problem. While much of Europe defended deep, often with markers and a sweeper, English clubs pushed up as a flat back four, with Tony Adams' upraised arm becoming the emblematic image of the all-too prevalent offside trap.

In the wake of the abysmal 1990 World Cup, however, Fifa began to tinker with the rules to stimulate attacking play. While this has been largely successful, the various adaptations of Law 11 have driven referees and linesmen, not to mention managers, players and fans, to distraction. The basic philosophy is that attackers are only "interfering with play" if they are receiving or playing the ball. But there is a whole host of uncertainties within that description not least, as Bill Shankly once said:"If he's not interfering with play, then what's he doing out there?"

For Fifa's interactive guide: http://www.fifa.com/en/regulations/regulation/0,3527,3,00.html