Canadian Criminal Evidence/Inferences

General Principles
An inference, like a presumption, is a method of establishing fact without direct evidence. An inference is discretionary on the judge to make, but it must be supported by evidence.

Any rational conclusion must be based on evidence. The ability of a judge to make inferences should be limited, otherwise it would leave the crown in the position where they would have to disprove "every possible conjecture, no matter how irrational or fanciful".

The difference between an inference and mere speculation is a fine line to distinguish.

Where the accused's post-offence conduct is "equally explained by" or "equally consistent with" two or more offences, there should be a "no probative value" instructions.

Failing to Call Certain Witnesses
The Crown does not need to call any witnesses it considers to be unnecessary. Likewise, the crown does not need to call unidentified witnesses or untrustworthy witnesses.

In some instances, an adverse inference may be drawn from a party's failure to call certain witnesses.

There are roughly two groups of inferences. First, the adverse inference will often be drawn where a party fails "to produce a witness reasonably assumed to be favourably disposed to that party"

Second, the inference may be drawn where the party failing to call has "exclusive" control over the witness.

The party failing to call must be given the right to explain the failure to call the witness.

The inference may only be drawn where there is no other reasonable explanation for the failure to call the witness.

Given the risk of shifting the onus onto the defence. Such an inference should only be drawn with the "greatest of caution" when dealing with an inference against the defence.