In New Jersey, consent searches are a common. Police use consent as a way to bypass the warrant requirement. This is especially the case with automobile searches. When the police pull a car over, and they suspect that drugs, weapons, or other contraband is inside, they may not always have probable cause to search. Or, they may be unsure if there is probable cause. Under normal circumstances, the police would have to show that an exception to the warrant requirement, like plain view, to search without a warrant. However, the police do not need probable cause to request consent to search. They can threaten you and tell you that they will apply for a warrant or get the dogs to sniff. This is legal. But you do not have to consent. They need reasonable articulable suspicion that something criminal lie within. See State v Carty
If you do consent, the State must show that your consent was knowing, voluntary, and not coerced. This will be a totality of the circumstances consideration for the judge hearing the case. The way you challenge a consent search is through a motion to suppress evidence. In this instance, the state would have to show that the consent was valid, and the defendant would argue that it was not.
Involuntariness is the issue almost always. All the facts that surrounded the incident will be heard by the judge as elicited from witnesses by both your defense attorney and the prosecutor. Although the police are allowed to engage in intimidating tactics, the use of those tactics will be considered as a factor in determining voluntariness. Other factors the court may consider are (just a few) was the defendant in custody (in cuffs, in the police car, in the station)? Was he advised of his right to refuse consent? Did the police make false claims regarding their probable cause to search? Did the police use overly intimidating or coercive tactics?
Bottom line is you will need a skilled criminal defense lawyer who has handled these types of situations before if you plan on challenging the consent search. I have a lot of experience in this area and actually understand the confusing body of case-law that has developed around this topic. For more information, reach out to me and I will provide a free consultation.