Flanagan, booked after the incident in the Ibrox side's 2-0 win over Celtic, was retrospectively charged but won an appeal against the Scottish FA ruling.

Celtic said the decision to not suspend the defender was a "huge embarrassment for Scottish football".

Now the Scottish FA has released its written reasons for the verdict.

Flanagan, 26, was shown a yellow card by referee Kevin Clancy after knocking Celtic captain Brown to the ground as they jostled at a corner.

Compliance officer Clare Whyte flagged the case to three former officials for further assessment, and they unanimously agreed the incident merited a sending off and Flanagan was given a two-game ban.

However, that was overruled by a fast-track tribunal on 17 May.

Under Scottish FA rules, an offence witnessed by a referee can only be retrospectively punished if it meets at least one of the following criteria - the involvement of excessive force, brutality or a resulting serious injury.

Whyte told the panel she would only be arguing that the clash featured brutality, which she defined as "savage, ruthless or deliberately violent".

After hearing Whyte, Flanagan and Rangers' lawyers present their cases - which included video replays of the incident - the panel sided with the former Liverpool player.

It rejected the compliance officer's claims that Brown had been struck in the face, insisting contact was made with the "chest/neck area of the opponent".

Flanagan insisted he was "merely fending off" the Celtic captain as he "stood his ground".

Explaining why they dismissed the notice of complaint, the panel concluded: "The referee saw the incident in question, and, notwithstanding that he did not see the actual point of contact, he saw sufficient to assess brutality and decided that the action of the player was reckless.

Their reasoning added that "the evidence did not meet the 'exceptional' test in judicial panel protocol 3.3."