Trainer Kris Lees has escaped charges over a positive swab to ibuprofen returned by City Of Justice who was treated at the same Victorian rehabilitation farm as several others to have returned the same result.

Racing NSW stewards conducted an inquiry on Monday into the sample taken from City Of Justice the day he won at Taree on January 19.

Stewards established the then-unraced City of Justice was treated at the rehabilitation centre with ibuprofen for a ligament injury between the September 29 and November 27, 2014 when trained at Caulfield.

After being alerted by stewards that City of Justice was displaying a low level of ibuprofen in a sample taken at Muswellbrook on August 2 last year, Lees ordered five tests at barrier trials before the horse was cleared to race after a negative result on December 2.

Stewards accepted that subsequent information from cases in both Victoria and NSW confirmed prolonged use of ibuprofen in rehabilitation regimes resulted in an unpredictable clearance of that drug from a horse's system.

Because Lees had proactively co-operated with stewards in undergoing a program of elective testing and was unaware of the 2014 treatment regime, stewards did not issue presentation charges against him.

City Of Justice was, however, disqualified from his win.

Victorian Group One performers Signoff and Lidari are among horses to have returned erratic test results after being treated with the anti-inflammatory.