Sport's top arbitrators said on Monday that FIFA had not fully complied with the world anti-doping code and there were no legal grounds to prevent football's governing body from doing so.
The Court of Arbitration for Sport (CAS) said in a statement that the primary sanction invoked by the World Anti-Doping Agency's (WADA) code, a two-year suspension for a first doping offence, did conform with Swiss law.
WADA chief Dick Pound had sought the court's opinion on the dispute with Zurich-based FIFA over anti-doping sanctions last November, after warning of a "potentially critical" situation ahead of the World Cup finals in Germany this summer.
Changes made by world football's governing body in September had failed to bring its rules fully into line with the world anti-doping code, according to WADA. FIFA had also approached CAS with its own evidence.
While recognising some legal issues, the CAS panel on Monday appeared to side largely with WADA's arguments in its "advisory opinion."
The panel "indicates that the FIFA code is not in full compliance with the WADC (world anti doping code) and that the deviations are not required by mandatory provisions of Swiss law," the statement said.
A major bone of contention is the application of a two-year ban for athletes, including footballers, who are caught doping the first time under WADA rules that are being applied in most sports. FIFA had rejected what it has called a "blanket sanction," saying it favoured penalties tailored to the offenders' degree of direct responsibility, and raising possible legal problems.
FIFA said on Monday that the CAS opinion had "confirmed" its practice of "using individual case management when sanctioning doping offences" and the legality of its own measures. However, football's governing body indicated in a statement that it was ready to make "the necessary adjustments" to its anti-doping provisions "independently," and would invite the CAS panel to help.
"With this legal opinion, which FIFA itself sought, CAS has laid the foundations for resolving any differences that exist with regard to the World Anti-Doping Code," FIFA president Sepp Blatter said. The advisory opinion is not binding like the court's usual arbitration rulings.
FIFA had done "everything in its power" to bring its disciplinary rules into line with the world anti-doping code, Blatter insisted last year.
In the 70-page ruling, the CAS said that it was up to sports organisations to adopt the world code "in accordance with their own decision making process."
"The panel also emphasises the fact that, to date, FIFA has not officially ratified or implemented the WADC but that the FIFA Congress 2004 indicated its unconditional support for the fight against doping and its respect for the WADC," the statement added.
The panel highlighted two potential legal flaws, one in the WADA code and another in FIFA's own modified rules. FIFA announced last month that at least four players from each of the 32 teams in the World Cup finals this summer will undergo random doping tests before and during the month-long competition.