Britain's three-day eventers emerged from a dramatic final day brandishing a team bronze and individual silver.
Leslie Law (left) celebrates silver
Leslie Law came second, while the team were given third place after a brief upgrade to silver.
But an appeal direct to the Court of Arbitration for Sport could see Law boosted to gold, GB to team silver and Pippa Funnell to individual bronze.
Winners Germany were demoted to fourth after Bettina Hoy infringed but won an appeal. Hoy then won individual gold.
French technical director Olivier Lepage: "The appeal jury have contradicted the judges on the ground. We do not agree with the decision, and nor do the British or Americans.
"We are going to go to CAS tomorrow. We are happy to have a silver medal burt it troubled us not knowing what colour we have.
"It disturbs our athletes and it was difficult for them to deal with. It seems to be a lobbying decision and not a sporting one.
Phil Pope BOA spokesman: "All three countries' chefs de mission are exploring their options. Clearly there are issues to be discussed."