In a civil case, what must the plaintiff demonstrate?

In a civil case, the plaintiff must demonstrate "preponderance of the evidence." This standard means that the evidence presented by the plaintiff must show that it is more likely than not that their claims are true. In practical terms, this is often understood as establishing that the likelihood of the claim's validity is greater than 50%.

This standard is less stringent than "proof beyond a reasonable doubt," which is the burden of proof used in criminal cases where the stakes are significantly higher, and the potential consequences for the defendant involve loss of liberty. The "clear and convincing evidence" standard, although used in certain civil cases involving issues like the termination of parental rights or the validity of a will, still does not apply uniformly across all types of civil litigation. Lastly, "reasonable belief" is not a formal standard of proof in legal cases but rather a subjective measure that does not satisfy the requirements of evidence needed to win a case.

Thus, the correct standard in most civil cases is indeed the preponderance of the evidence, as it strikes a balance appropriate for the nature of civil litigation, allowing for resolution of disputes without the heightened burden present in criminal law.