Uefa president Michel Platini believes European law will scupper plans by world soccer bosses to limit the number of foreign players in club competitions.
World governing body Fifa hope to impose a policy which would ensure all clubs field at least six homegrown players in their starting line-ups by 2010.
Platini contends, however, that an individual's legal freedom to seek employment in any of the continental union's member nations means there is no way Fifa could make such a ruling.
"It's impossible," Platini told Sky Sports News. "We cannot defend that today; we do not have the legal framework.
"The free movement of workers is the number one rule in Europe."