1985 was a grim year for English football. The FA Cup Sixth Round encounter at Kenilworth Road in March had seen Millwall fans run amok from before kick-off; Heysel; a teenage boy died at Birmingham. Margaret Thatcher presented her brainwave of ID Cards via her lapdog Minister for Sport, Colin Moynihan (now Lord and Chairman of BOA).
Cures had been in short supply with football authorities and governments over the years failing to grapple with the social issues that were intertwined with the hooliganism problem.  Suggestions over the years had ranged from segregation through to the ill-conceived electric fences proposed for Stamford Bridge by Ken Bates. Stadia at the time were decrepit at best; facilities now that seem embarrassing to think of. Treating the supporters like animals merely served to imflame situations.
Relatively speaking, Highbury was at that time reasonably safe to visit. There were problems, a barrier gave way in 1972 against Derby in an FA Cup tie whilst West Ham had made some infamous visits to the North Bank. There were incidents but compared to other grounds, these were not as plentiful. At a time when violence was reaching it's low point, Arsenal had relatively few arrests as noted by Ken Friar below.
The article gives an interesting insight into the club's view on the issue.