In order for a police officer to look at your engine, they must have probable cause or a warrant. Without probable cause or a warrant they must have consent from the you, so if they say " pop the hood" and you say " no" they cant do anything about it. they might say something casual like "you mind if you pop ur hood?" if you answer yes then they would have consent.
Probable cause-n. sufficient reason based upon known facts to believe a crime has been committed or that certain property is connected with a crime. Probable cause must exist for a law enforcement officer to make an arrest without a warrant, search without a warrant, or seize property in the belief the items were evidence of a crime . While some cases are easy (pistols and illicit drugs in plain sight, gunshots, a suspect running from a liquor store with a clerk screaming "help"), actions "typical" of drug dealers, burglars, prostitutes, thieves, or people with guilt "written across their faces," are more difficult to categorize. "Probable cause" is often subjective, but if the police officer's belief or even hunch was correct, finding stolen goods, the hidden weapon or drugs may be claimed as self-fulfilling proof of probable cause. Technically, probable cause has to exist prior to arrest, search or seizure.
next time a cop pulls you over for a license plate and ask/tells you to pop your hood ask "for what ? I did not do anything wrong", see if the cop justifies his/her search
btw, if the cop gives you a hard time saying that he doesnt need prob cause or says he does but doesnt explain it or isnt justified, take him to court and the case will be thrown out and ruled in your favor because even if you do have an illegal engine (its not illegal to own it, its illegal to use it),it wouldnt matter bc that part of the evidence would be decalared unconstitutional and invalid in court bc the information/evidence was obtained infringing your 4th amendment rights and was obtained unconstitutionally. therefore making the case hollow.
PHILOSOPHY AND ENGLISH ROCKS!!!!! :ylsuper
Hope this helps and is used for future reference
