probable cause

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Reasonable suspicion of the presence of evidence of criminality, allowing the search of the person or premises for such evidence by authorities.
• noun Reasonable grounds for believing a person is guilty of a criminal act, allowing the arrest, prosecution, or trial of such person.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun US The standard by which a police officer may make an arrest or conduct a personal or property search.
• noun In accident investigations, the conclusions reached by the investigating body as to the factor or factors which caused the accident.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun (law) evidence sufficient to warrant an arrest or search and seizure