Probable Cause: a reasonable suspicion or belief that a person or persons has or is in the process of committing a crime. This is a requirement for an arrest to be made.
Reasonable Suspicion: An observation or belief that a person or persons is engaged in an activity that may be criminal in nature. This is required to initiate an investigation.
As can be seen by analyzing the words used in the definitions that they purport a very close relationship. To the street cop the difference is immaterial as the action he would take is essentially the same in either case. Hence, my earlier statement that they are one and the same. The difference in degree is one of splitting hairs but it sounds good to make a distinction. Both require a resonable belief.
a non-primary (secondary) statute is one that is not actionable until and unless a primary statute is invoked first. In some state the wearing of a seat belt is a secondary offense. In such a case a police officer cannot stop a car where the driver is noticably not wearing the seat belt. But if a driver is stopped for speeding then the seat belt law can be invoked and applied to the situation. This is the case with the AZ immigration law, a law enforcement officer cannot act upon a suspicion that someone might be illegal (such as not being able to speak a word of English) unless a primary offense presents itself. So in order for a law enforcement officer to even begin to inquire as to someone's legal/illegal status an actionable offense must have occurred first.
BTW: It is the law in every state that providing Identification to police is a requirement. Any person, citizen or not, can be detained until evidence establishing their identy is presented. Acceptable forms of ID are: Driver's license, Passport, notorized Birth Certificate along with a picture, or some other form acceptable to the inquiring agency but a picture is a required part thereof, but can be waived by witnesses testiment. The Driver's license, being a legal form of ID, is where many states aid the illegal immigrant by not requiring proof of citizenship before issuing a license. But even the request for ID is a secondary statute.
Probable cause works like this: a cop sees a vehicle which appears to be traveling at a high rate of speed or a speed over and above that of the posted speed limit (and believe me, a good traffic cop can call the speed of a vehicle within a mile or 2 of its real speed) and begins pursuit during which a pacing (matching apeed by maintaining a set distance) said vehicle and upon finding that it is indeed exceding the speed limit stops the vehicle and requests (In Washington State) Driver's license, vehicle registration, and proof of insurance. The Driver, not possessing a DL is then detained until proper identification can be established. Whereupon the driver is cited for the spedding and No vehicle operator's license on person (NOVOLOP in coop jargon).
Or a person hanging around the local 7-11 for several hours raises the suspicion of the clerk on duty, who calls the police who then investigates the reasonable suspicion of a complaintant.
DUI can only be enforced as a secondary offense as some other violation initiates the traffic stop, weaving, irratic speed, no lights, crossing the center or fog line several times in a short distance, etc. Once stopped the driver is, again, asked to provide ID and if the odor of intoxicants, slurred speach, stumbling, dialated pupils, etc are observed then the offense of DUI can be investigated. Setting in the driver's seat of a stationary vehicle is not DUI, unless the engine is running, but Physical Control while Intoxicated.
I hope by this time, and the definitions and examples given, that a better understanding of how primary and secondary offenses work and see that the AZ immigration law is initiated. But to make it even clearer I'll explain profiling.
Profiling: Just requesting papers because of a persons skin color is profiling ,as the liberals claim, and it is tossed out of court every time. Skin color alone is not profiling when it is a primary factor in establishing identification. Such as "the bomber appeared to be a man of middle eastern decent." Or, "the bank robber was described as a black man about 6 ft tall." Also since illegal immigrants come from all continents of the world, just focusing upon persons of a single skin color, is not proper enforcement of the law. So a case can be made that focusing on persons of a single ethnicity is racial profiling except in cases where the degree of ethnic population is well above the norm. Which means that in the border states it would be hard to establish racial lprofiling using ethnicity as the sole factor.
The Left choses to ignore how the application of the law is actually done, taking a few facts, to distort the message and twang the heartstrings of emotion. Just because you "feel" somethings wrong doesn't mean that it is. If logical analyzsis causes you to think something is wrong, then it probably is. One is an emotional response, the other is a reasonable belief.