The presumption of innocence is not relevant to the scenario shown in the video. Guilt or innocence are determined in a Courtroom by Judge and/or Jury. Presumption of innocence means that once a case gets into Court, it is up to the prosecution to prove guilt beyond a reasonable doubt as opposed to the accused having to proved their innocence.
Not true!
We, as citizens of this nation, have a Constitutional Right against unwarranted search and seizure. And that right is based upon the presumption of innocence.
We do not live in a police state where the police can question a person for no good reason (at least not yet).
It's this "cops have the right to do anything" mentality that gets cases thrown out of court for lack of probable cause.
Actually it is true. Cops do not determine innocence or guilt, that happens in the Courtromm, not on the street. The "presumption of innocence" AKA "Innocent until proven guilty" governs what has to happen in a Courtrom for a defendant to be convicted of the charges against him. With our system, the burden of proof is on the prosecution. If the prosecution is not able to prove beyond a reasonable doubt that the defendant committed the ccrime, the defendant is set free. In the contrasting system of "guilty until proven innocent", the mere fact of being charged in court establishes a presumption of guilt, and it is up to the defendant to prove his innocence. Fortunately, The United States does not use the latter system. Once again, since the video in question showed a legal police contact that did not result in an arrest, let alone a trial, the whole issue of innocent until proven guilty is moot.
You are most certainly correct that our Constitution's 4th Amendment limits the police's legal ability to collect evidence. However, collection of evidence does not get into guilt or innocence and in fact uses a much lower standard that what is used in the courtroom i.e. "probable cause".
To understand that, consider your analogy of a person carrying a cellphone. Although a person could be carrying a stolen cell phone, a police officer would be unable to detain the person and see if the cell phone was stolen unless he had probable cause to believe that is was actually stolen. A citizen's report of a "suspicious man carrying a cell phone" would not constitute probable cause. If a cop were detain your hypothetical cell phone carrier without probable cause, any evidence that came from that contact would be inadmissible in a court. Likewise, if the police wanted set up trace on your cell phone, they would need to present "probable cause" to a judge to get a court order. Again, the cop would not need to prove to the judge that the person was guilty of anything, but merely establish of a probable cause of a crime.
I do agree with you that we do not live in a a police state where the police can question a person for no good reason. Of course with respect to the video, as previously cited, California law specifically and unambiguosly grants LEOs the legal authority to detain a person carrying a handgun to determine its loaded status. Because the incident occurred in California, North Carolina laws are irrelevant.
As far as asking for identification, I still have not heard anyone cite any law would prohibit Officer Lyons from making that request. After the pedestrian excerised his right to not provide identification, Offcier Lyons courteously let him on his way, further supporting your statement that we do not yet live in a police state.
