In April this year, Switzerland's FC Sion were punished for a similar offence over the signing of Egyptian goalkeeper Essam El Hadary from Al-Alhy. It was banned from signing any new players until next summer and El Hadary received a four-month ban.
But after Sion appealed to CAS, the sanctions were frozen while it considers the case, allowing the club to trade during the summer, with a judgment expected later this year. Chelsea are strongly expected to follow a similar route once they receive the full legal grounds for the ruling.
In May, a ruling over Brazlian player Matuzalem was upheld by CAS when he transferred from Shakhtar Donetsk to Reak Zaragoza. In that case the Spanish club were not accused of inducing the player to break his contract but were still made jointly liable for the €11,858,934 fine imposed by CAS.
"Considering the decision passed by CAS in the Matuzalem case in general, Fifa is satisfied that its efforts to defend contractual stability in the world of football are backed by CAS," it said at the time. "In fact, this is an issue in which it is crucial that FIFA, representing the entire football world, and CAS are pulling in the same direction."
In 2004, Roma were also given a ban for two transfer windows following defender Philippe Mexes' move from Auxerre. Roma appealed to the CAS and had the ban cut to one transfer window.