The Laws of Football clearly state that most forms of contact in a marking contest are prohibited unless the infringer is also attempting to mark the football. Gradually over the last 20 years this has been lost and now it is fair to make contact if the infringer is simply attempting to spoil rather than mark.
The flagrant disregard for this rule has seen the demise of a number of great attributes of our game: the contested mark, the hundred goal full forward, the long kick, strong marking backmen and to a lesser extent the rover at the foot of the pack. At the same time it has promoted flooding, double teaming and scragging before the ball arrives.
To give us back the game we love nothing has to change, somebody just needs to reed the rules.
15.4.3 Permitted Contact
Other than the Prohibited Contact identified under Law 15.4.5, a
Player may make contact with another Player:
(a) by using his or her hip, shoulder, chest, arms or open hands
provided that the football is no more than 5 metres away from
the Player;
(b) by pushing the other Player with an open hand in the chest or
side of the body provided that the football is no more than 5
metres away from the Player;
(c) by executing a Correct Tackle;
(d) by executing a Shepherd provided that the football is no more
than 5 metres away from the Player; or
(e) if such contact is incidental to a marking contest and the Player
is legitimately Marking or attempting to Mark the football.
15.4.5 Prohibited Contact and Payment of Free Kick
A field Umpire shall award a Free Kick against a Player where he or
she is satisfied that the Player has made Prohibited Contact with an
opposition Player.
A Player makes Prohibited Contact with an opposition Player if he
or she:
(a) makes contact with any part of his or her body with an
opposition Player;
(i) above the shoulders (including the top of the shoulders
or bump to the head); or
(ii) below the knees.
(b) pushes an opposition Player in the back, unless such contact
is incidental to a Marking contest and the Player is legitimately
Marking or attempting to Mark the football;