EACL does not have an official policy on best paper awards, imposed top-down by the Board. It is essentially the job of the program chairs to decide whether to have best paper awards (and how many), and to implement a policy to determine how to pick a winner. EACL-12 did have an award. A 6-person committee chaired by Stephen Clark (at the request of the program chairs) made the decision, after being presented with a number of worthy papers suggested by the program chairs and members of the program committee.
Stephen Clark. October, 2013