Victorian stewards will fight a Supreme Court decision to overturn trainer Mark Riley's three-year disqualification.

Riley was outed after the Racing Appeals and Disciplinary Board found him guilty of a charge relating to higher than allowable levels of TC02 in one of his horses.

The Victorian Civil and Administration Tribunal agreed with the ban and Riley took his case to the Supreme Court which ruled in his favour.

Justice Kevin Bell said the stewards, the RAD Board and VCAT had erred in accepting the rounding up of the higher of two samples tested at different laboratories.

The sample showed a level of 37.0617 millimoles per litre of plasma which Justice Bell said should be taken as 37, not 37.1.

He said allowing for the 1mmol/L measure of uncertainty the level should be read as 36, the legal limit.

RV stewards confirmed they would seek leave to appeal Justice Bell's decision.