From the Decision in Terry vs. Ohio:
http://caselaw.lp.findlaw.com/cgi-bin/getcase.pl?court=us&vol=392&invol=1
"We do not retreat from our holdings that the police must, whenever practicable, obtain advance judicial approval of searches and seizures through the warrant procedure, see, e. g., Katz v. United States,
389 U.S. 347 (1967); Beck v. Ohio,
379 U.S. 89, 96 (1964); Chapman v. United States,
365 U.S. 610 (1961), or that in most instances failure to comply with the warrant requirement can only be excused by exigent circumstances, see, e. g., Warden v. Hayden,
387 U.S. 294 (1967) (hot pursuit); cf. Preston v. United States,
376 U.S. 364, 367 -368 (1964). But we deal here with an entire rubric of police conduct - necessarily swift action predicated upon the on-the-spot observations of the officer on the beat - which historically has not been, and as a practical matter could not be, subjected to the warrant procedure.
Instead, the conduct involved in this case must be tested by the Fourth Amendment's general proscription against unreasonable searches and seizures.
17
Nonetheless, the notions which underlie both the warrant procedure and the requirement of probable cause remain fully relevant in this context. In order to assess the reasonableness of Officer McFadden's conduct as a general proposition, it is necessary "first to focus upon [SIZE=-1]
[392 U.S. 1, 21] [/SIZE]the governmental interest which allegedly justifies official intrusion upon the constitutionally protected interests of the private citizen," for there is "no ready test for determining reasonableness other than by balancing the need to search [or seize] against the invasion which the search [or seizure] entails." Camara v. Municipal Court,
387 U.S. 523, 534 -535, 536-537 (1967).
And in justifying the particular intrusion the police officer must be able to point to specific and articulable facts which, taken together with rational inferences from those facts, reasonably warrant that intrusion. 18 The scheme of the Fourth Amendment becomes meaningful only when it is assured that at some point the conduct of those charged with enforcing the laws can be subjected to the more detached, neutral scrutiny of a judge who must evaluate the reasonableness of a particular search or seizure in light of the particular circumstances.
19 And in making that assessment it is imperative that the facts be judged against an objective standard: would the facts [SIZE=-1][392 U.S. 1, 22] [/SIZE]available to the officer at the moment of the seizure or the search "warrant a man of reasonable caution in the belief" that the action taken was appropriate? Cf. Carroll v. United States,
267 U.S. 132 (1925); Beck v. Ohio,
379 U.S. 89, 96 -97 (1964).
20 Anything less would invite intrusions upon constitutionally guaranteed rights based on nothing more substantial than inarticulate hunches, a result this Court has consistently refused to sanction. See, e. g., Beck v. Ohio, supra; Rios v. United States, 364 U.S. 253 (1960); Henry v. United States, 361 U.S. 98 (1959). And simple "`good faith on the part of the arresting officer is not enough.' . . .
If subjective good faith alone were the test, the protections of the Fourth Amendment would evaporate, and the people would be `secure in their persons, houses, papers, and effects,' only in the discretion of the police." Beck v. Ohio, supra, at 97. "
Terry is about more than just whether or not a person can be patted down. It also includes the Court's citation about having to have cause for the stop in the first place.
Good faith on the part of the office is not enough. There has to be probable cause or reasonable suspicion that a crime has been committed. Terry, including the citation to Beck.