The party with the burden of proof in a civil action (e.g., the plaintiff or cross-complainant) generally must prove its case by a preponderance of the evidence. To meet this burden, the jury must be persuaded, by the evidence in court, that the fact(s) to be proven are more likely true than not true. Where the jury cannot decide something is more likely to be true than not true, it must conclude the party did not prove it. In making its decision, the jury must consider all the evidence, irrespective of which party presented it.
This post is for informational purposes (see disclaimers). Credit is due to CACI jury instructions.