By Tom Fordyce

Ten years ago this Friday, the European Court of Justice passed a ruling that presaged a revolution in European football.

The desire of Jean-Marc Bosman to move from Club de Liege to Dunkerque inadvertently triggered a change in the law that altered the face of football forever.

Little did the low-profile midfielder from Belgium realise what his court action was about to do ...

Before Bosman, a player could not leave unless his club agreed to let him go.

THE BOSMAN RULING EXPLAINED On 15 December 1995, the European Court of Justice ruled that players should be free to move when their contracts had expired It also ruled that EU clubs could hire any number of European Union players

After the ruling, a player was free to leave as soon as his contract expired.

Result? The player became the boss.

Free-agent players moving clubs could demand huge signing-on fees and salaries, on the basis that the club they were joining had not had to pay a penny in transfer fees.

Clubs became powerless to stop their best players leaving at the end of their existing deals.

And players under contract could ask for bigger and better deals for staying put - because they could threaten to leave for free if the club failed to accede to their demands.

Pre-Bosman, clubs were limited in the number of foreign players they could sign.

In European competitions, Uefa regulations decreed that clubs could field only three foreign players plus two "assimilated" players who had come through their youth set-up.

Post-Bosman, clubs could sign any number of players from European Union countries.

That made possible the phenomenon of clubs fielding teams without a single player from that country.

Without the Bosman ruling, Chelsea and Arsenal could never have fielded teams without a single British player, as both have famously done.

When players became more powerful, so did their agents.

Agents were able to pick up fees from a club for bringing an out-of-contract star player to them, and take their cut of the signing-on fees and loyalty bonuses that they demanded for their clients.

The savvy amongst them were able to set themselves up as international operators, acting as negotiators for the overseas footballers pouring into the European leagues and as unofficial scouts - or touts - for the clubs signing them.

Did Bosman help Manchester United win the Champions League?

British clubs pre-Bosman found themselves at a huge disadvantage in European competitions, because Uefa decreed that Welsh and Scottish players counted as foreigners under their "three-plus-two" rule.

That meant that United, for example, had to make wholesale changes to their normal line-up when playing in Europe - most memorably when Alex Ferguson brought English goalkeeper Gary Walsh in for the Danish Peter Schmeichel in the 4-0 thrashing by Barcelona in 1994-5.

When clubs were suddenly freed to play all the EU players they wanted, Sir Alex Ferguson was at last able to play his first-choice XI in Europe.

Only five of the 13 players who featured in United's 1999 Champions League final win over Bayern Munich were English.

Before the Bosman ruling, that team could never have set foot on the pitch.

Clubs were forced to pay higher wages to players post-Bosman - and that meant that they sought to boost their revenues accordingly.

The average fan ended up footing some of the bill, partly through increased ticket prices but also for the television packages that allowed them to watch the new millionaires from the comfort of their own homes.

To prevent their best players leaving on a Bosman transfer - and thus costing them potential millions in lost transfer fees - clubs began signing their star names to long-term deals.

BIG BOSMANS Sol Campbell Spurs to Arsenal, 2001 Patrick Kluivert Ajax to Milan, 1997 Steve McManaman Liverpool to Real Madrid, 1999 Brian Laudrup Rangers to Chelsea, 1998 Jean-Alain Boumsong Auxerre to Rangers, 2004

When the times were good and the money flowing in, this wasn't a problem.

But when times got tough - when clubs were relegated, or when television deals like the ITV Digital one collapsed - these long-term contracts became millstones around the clubs' necks.

Leeds, Sheffield Wednesday, Bradford City and Derby were all left paying non-performing players huge weekly salaries.

Leeds were just one of many clubs forced to sell their brightest talents - like Jonathan Woodgate, Olivier Dacourt, Paul Robinson and Mark Viduka - at cut-price rates, just to get their salaries off the pay roll.

The smaller clubs like Bradford, who could only attract big names with big salaries, were hit hardest.

But even giants like Chelsea found themselves haemorrhaging cash - like the £40,000 a week they paid Bosman signing Winston Bogarde for his 12 appearances in four years.

The smaller clubs could no longer rely upon transfer fees to boost their coffers.

Whereas before they could develop home-grown talent and know that they could sell it on to the big boys, their best young players could leave for free at the end of their deals.

The rich clubs, at the same time, were the only ones who could afford to match the biggest stars' newly-inflated salaries.

And the pool of money available to the big clubs was increasingly diverted to the pockets of out-of-contract foreign players and their agents rather than going on transfer fees to lower league teams

As UEFA chief executive Lars-Christer Olsson explains: "Those clubs who had access to all the money started to rob the smaller clubs, not just to get stronger themselves but to weaken the opposition."

Ironically, Bosman himself was left bereft by his far-reaching court action.

He started his case in 1990 when he was 25 and in the prime of his career, was left in limbo for five years and then, one year after he won, he had to leave third division Vise because he said he could not make a living out of it.

He is now reduced to living off his court indemnities.

Bosman's lawyer Luc Misson says: "He gave his career to a court case to serve a cause, but he sees that the transfer fees are still there, quotas on home-grown players are making a comeback and the rich clubs are richer and the poor ones are poorer."