Brinegar v. United States

In Brinegar v. United States, 338 U.S. 160 (1949), the United States Supreme Court described the concept of probable cause as follows: "In dealing with probable cause as the very name implies, we deal with probabilities. These are not technical; they are the factual and practical considerations of everyday life on which reasonable and prudent men, not legal technicians, act." Moreover, "probable cause exists where 'the facts and circumstances within their the officers' knowledge and of which they had reasonably trustworthy information are sufficient in themselves to warrant a man of reasonable caution in the belief that' an offense has been or is being committed." Brinegar, supra, at 175-76. The Court stated that, "in dealing with probable cause, . . . as the very name implies, we deal with probabilities. These are not technical; they are the factual and practical considerations of everyday life on which reasonable and prudent men, not legal technicians, act. The standard of proof is accordingly correlative to what must be proved." The Court noted that "this means less than evidence which would justify condemnation or conviction." Id. at 175. Instead, probable cause exists when the facts within the police officers' knowledge -- where they had reasonably trustworthy information -- are "sufficient in themselves to warrant a man of reasonable caution in the belief that an offense has been or is being committed." Id. at 175-76. The Court explained that, "because many situations which confront officers in the course of executing their duties are more or less ambiguous, room must be allowed for some mistakes on their part. But the mistakes must be those of reasonable men, acting on facts leading sensibly to their conclusions of probability." Id. at 176