Comment: There is life in Mars, but just not as much as some suggest

What do a roll of duct tape and a pizza box have in common?  Apparently they are both good sources for the discovery of fingerprints.  However, the discovery of a fingerprint on them likely wont give rise to the same inferences a recent Ontario Court of Appeal has held.
Thomas Wong and Paulo Stein broke into a home and confined the occupants.  At trial the only issue was identification.  They were convicted.  Their appeal was recently dismissed: R v Wong, 2011 ONCA 815.
On appeal they argued that their convictions should be overturned.  The central piece of evidence against them was the discovery of Stein's fingerprint on the inside of a duct tape roll used to bind the victim and Wong's DNA on a construction mask matching the description of the one worn by one of the assailants.  The appellants argued that this was not sufficient to justify a conviction.  In support they relied upon R v Mars, 2006 CarswellOnt 722 (CA).
In dismissing their appeals the Court of Appeal offered the following explanation and distinction of Mars:
The other evidence, which he reviewed carefully, included the fact that the descriptions of the perpetrators generally conformed to the appearance of the appellants; the mask containing Wong’s DNA matched the description of the mask worn by the Chinese perpetrator; and considered the pristine condition of the mask and where it was found in relation to the position of the back door and yard gate. He also considered where the duct tape was found and where the fingerprint was located in the context of all the evidence about the duct tape and strands of duct tape.
The facts of this case are quite different to those in Mars. There is a great difference between a construction mask and the inside cardboard of a roll of duct on one hand and a pizza box on the other. Several people sharing a pizza may leave their prints on the pizza box, before two of them use it in a home invasion. The circumstances in which Wong's DNA could come to be innocently deposited on the inside of the pristine construction mask or Stein's fingerprint could be impressed on the inside of a roll of duct tape used in the crime, in our view, are in the realm of speculation rather than reasonable inference.
In addition, it is significant in Mars that the force of the fingerprint evidence was diminished by exculpatory identification evidence. Here, we do not accept that the descriptions of the perpetrators were exculpatory. In our view, the trial judge's finding of fact that the victims' descriptions of the perpetrators generally conformed with the appearance of the appellants was supported by the evidence [paras 4-6].
This explanation and distinction of Mars is an important one; especially coming from the very court that rendered the decision.  Mars is a case which is often cited in support of this type of argument.  In O'Brien, for example, it was cited on appeal as support for the argument that DNA found on a mask used in a robbery could not support a conviction.  That argument was rejected on appeal: 2010 NSCA 61; aff'd on other grounds 2011 SCC 29
Similarly in Samuels, Mars was cited on appeal to support the argument that a "palm print and fingerprint on the lower driver's side corner of the front windshield of the car parked two houses away" was helpful in supporting a conviction for, inter alia, robbery and aggravated assault.  That argument was also rejected on appeal: 2009 ONCA 719.  The following conclusion in that regard is instructive:
However, unlike Mars, there is other evidence capable of permitting a reasonable inference that the palm print and fingerprint on the windshield were placed there when one of the invaders fled the scene:
(a)              The evidence of Mr. Barreira that the last man out of the house ran down the street and leapt over the front of the car;
(b)            The evidence of Mr. Barreira that the man grabbed the car as he jumped over it;
(c)            The palm print and fingerprint faced a direction that was consistent with Mr. Barreira’s description of the invader’s flight path.  The opinion of the expert witness that the impressions exhibited movement from the driver’s side toward the passenger’s side of the car is also consistent with the description of the flight path;
(d)            The footprint in the mud approaching the car, the fresh dent and the mud on the car are consistent with Mr. Barreira’s description of the flight; and
(e)            The evidence of the owner of the car that it was undamaged before he went to bed on the night of the home invasion.
Mars is a helpful and important decision which reminds us about the limits of fingerprint and DNA evidence in establishing identification.  However, the attempt to rely upon Mars in cases like Samuels, O'Brien and Wong are misplaced; they ignore the fact that the reasonableness of a verdict will depend upon the the particular facts of a given case and must be assessed in light of all the facts.  The caution offered by Doherty JA in Mars is an apt conclusion to this comment:
As reasonableness is ultimately a fact-based determination, prior decisions, even those made in similar cases, cannot have binding authority [para 5].
DG Mack