Know Your Rights

Preponderance of the evidence, also known as balance of probabilities is the standard required in most civil cases. The standard is met if the proposition is more likely to be true than not true. Effectively, the standard is satisfied if there is greater than 50 percent chance that the proposition is true. Lord Denning, in Miller v. Minister of Pensions,[3] described it simply as "more probable than not." Until 1970, this was also the standard used in juvenile court in the United States.

http://en.wikipedia.org/wiki/Legal_burden_of_proof#Preponderance_of_the_evidence