A video recording of the incident in question was viewed during the hearing which was held at the Millennium Stadium on Wednesday, 31 December, 2008.
During the Scarlets recent injury crisis, the adaptable Priestland has found himself at full-back and come through as one of the few shining lights in a miserable campaign so far in Nigel Davies's side.
For the Dragons clash tomorrow, Davies has recalled the international trio of Stephen Jones, Matthew Rees and captain Simon Easterby.
The Dragons are missing injured duo Luke Charteris and centre Rhodri Gomer-Davies, but field new signing Nigel Hall, a prop from Nottingham, in their squad.
Scarlets: M Stoddart; G Morris, R King, J Davies, M Jones; S Jones, M Roberts; P John, M Rees, D Manu, D Day, S Maling, S Easterby (capt), J Edwards, D Lyons. Replacements: C Cross, M Schwalger, L Reed, D Jones, G Cattle, R Priestland, D Daniel