If, during a lawful pat-down search, an officer feels an object whose mass makes it immediately identifiable as contraband, that officer can seize the item. This is considered, very loosely, the "plain feel" doctrine.
These are cases where the officer frisks someone for weapons or contraband. So, if you have a possession case in Bucks County, you would want to explore with your Bucks County criminal lawyer how the drugs were found. If it was pursuant to a simple frisk/pat-down, your lawyer better know the law.
A case guiding this situation is Commonwealth v. Stevenson.
Stevenson had two cases. In the first case although the officer felt what he described as a cigar or cigarette and a pill bottle during his frisk, he did not plainly feel, objects that were immediately apparent to him as contraband. The officer in the second case testified that during the frisk of defendant, he felt three hard packages of folded paper or cardboard in the change pocket of defendant's jeans. Since the officer offered only vague assertions that he somehow "knew" the cardboard was drugs based on "the feel of the bulge," the record did not support a finding that it was immediately apparent that the cardboard was contraband. Because the pat-down of defendant failed to establish probable cause, the subsequent search of the trunk of the car, was likewise unconstitutional. Thus, the drugs recovered from defendants' person as well as from the trunk of the car must be suppressed. The outcome was that the Supreme Court ruled that the orders of the lower courts were reversed, because the officers did not "plainly feel" contraband when frisking appellants, and there was therefore no probable cause to search the trunk of the car, thus the drugs recovered were suppressible. Commonwealth v. Stevenson, 560 Pa. 345 (Pa. 2000).
Another interesting case is Thompson. The appellate court held in Thompson that defendant waived his claim that the initial stop was a pretext for an unlawful seizure. The officer had information from another officer that defendant was driving with a suspended license, which gave the officer reasonable suspicion that defendant was violating a provision of the vehicle code and justified the initial stop under 75 Pa.C.S. § 6309(b). Defendant was "uncomfortable and fidgety," refused to keep his hands in plain view, and attempted to drive away. Defendant also reached into his pocket when specifically directed by the officer to keep his hands in view, leading the officer to believe defendant might have been reaching for a gun. The officer articulated specific facts from which he could reasonably infer that his safety was compromised, and justified subjecting defendant to a Terry frisk. However, there was no evidence that digital scale and currency in defendant's pocket felt like weapon or were immediately recognizable as nonthreatening contraband. The subsequent canine sniff, warrant, and search of defendant's car were unlawful, and the drugs later seized from defendant's car were tainted fruits of an unlawful search. Commonwealth v. Thompson, 2007 PA Super 372 (Pa. Super. Ct. 2007)