What is the test for establishing a prima facie case?

In the instant case I am satisfied that facts have been established by the Crown from which it may reasonably be inferred that the accused drove his vehicle at a speed greater than was reasonable and safe, having regard to the circumstances prevailing at the time. Accordingly, there is a prima facie case. A burden is then cast upon the accused to establish that his speed was reasonable and safe under the existing circumstances. That burden is satisfied upon the accused adducing evidence that would carry proof on a balance of probabilities: Regina v. Appleby, supra. The accused has not done so in the instant case. In fact, the accused offered no evidence.