A fundamental principle of our system of criminal law is that the Defendant is presumed to be innocent. The mere fact that he is arrested, and is accused of a crime, is not any evidence against him. Furthermore, the Defendant is presumed innocent throughout the trial and unless and until you conclude, based on careful and impartial consideration of the evidence, that the Commonwealth has proven him guilty beyond a reasonable doubt.
It's not the Defendant's burden to prove that he is not guilty. Instead, it is the Commonwealth that always has the burden of proving each and every element of each crime charged and that the Defendant is guilty of those crimes beyond a reasonable doubt.
If the Common wealth's evidence fails to meet its burden on any one of the charges then your verdict must be not guilty. On the other hand, if the Commonwealth's evidence does prove, beyond a reasonable doubt, that the Defendant is guilty, then your verdict should be guilty.
Although the Commonwealth has the burden of proving that the Defendant is guilty, this does not mean that the Commonwealth must prove its case beyond all doubt, or to a mathematical certainty, because there are few things in life that we can be absolutely certain about.
Nor must it demonstrate the complete impossibility of innocence. A reasonable doubt is a doubt that would cause a reasonably careful and sensible person to hesitate before acting upon a matter of importance in his or her own affairs.
A reasonable doubt must fairly arise out of the evidence that was presented, or out of the lack of evidence presented, with respect to some element of the crime.
A reasonable doubt must be a real doubt. It may not be an imagined one, nor may it be a doubt manufactured to avoid carrying out an unpleasant duty.
So, to summarize, you may not find the Defendant guilty on mere suspicion of guilt. The Commonwealth has the burden of proving the Defendant guilty beyond a reasonable doubt with respect to each of these charges. If it meets that burden, then the Defendant is no longer presumed innocent, and you should find him guilty.
On the other hand, if the Commonwealth has not met its burden, then you must find him not guilty.
[Source: Given and approved in Commonwealth v. Janda, 2010 Pa. Dist. & Cnty. Dec. LEXIS 117, 69-74 (Pa. County Ct. 4/22/2010, No. CR-703, 4266-2008).]
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PG VII(G) - Burdens and Presumptions: Allocating the Burden of Proof as to Statutory Exception to Liability