Because firearm offenses often involve defendants who are prohibited from possessing a firearm, just the mere possession alone would be an offense. In terms of common defenses, often, the argument would be that the person charged with the firearm offense was not in possession of the firearm. Unless the firearm was recovered from the person's actual person at the time of the arrest, for example, say two people are in a car and a firearm is found in the center console. If the passenger, for example, were to be charged, your argument would be, well, it's not the passenger's car.
The implication or the expectation would be that the charge should be connected with the driver, especially if it's the driver's car. It's going to depend on a number of factors in terms of like who gets charged or if both people get charged. Often, the argument would be that a person's not in possession of the actual firearm, or for example, say if the police conducted an unlawful search to recover the evidence, to recover the firearm, an attorney would file a motion to suppress evidence, the evidence being the firearm.
f that evidence is suppressed, the prosecution would not be able to use that evidence against the defendant. There's various resources and tools and experienced attorney can use. Because a firearm offense is so serious, you should have an experienced Pennsylvania criminal defense attorney in your corner from as early as possible in the process.