You have the right to record your interactions with law enforcement, subject to limited exceptions. In any public space you may record anything in plain view. On private property, the owner of the property may set the rules for recording. The police may order citizens to not interfere with their legal police work, however, the mere act of recording something typically does not interfere with police work. However, crossing police lines, or being close to an area where an arrest is occurring may interfere with police work. So keep a safe distance from police activity and if the police ask you to leave an area, step a safe distance away and continue recording.
And makes sure that it's clear you are holding a camera, and not a weapon. If questioned what you are doing identify that you are holding a phone. If the officer seems to think you are holding a weapon immediately put the phone down. It will continue to record, and you will remain alive.
Please take a few minutes to watch the embedded video, which includes excellent advice as to how to record the police.
B. Making Useful Video
When recording, do not provide "color commentary". If helpful, provide only basic information such as what happened before the video started, and minimal context. Try to keep the video fairly zoomed out to capture the entire scene, rather than having close up footage.
If you are not directly involved in the incident, we suggest that overt recording of the interaction is always best. If you are subject to questioning, you may, from a practical perspective, escalate a conflict by overtly recording an interaction, so judgement should be used. However, apps like Hands Up allow you to discretely record interactions, as the app turns your phone screen off during the recording.
C. Apps to Preserve the Video From Deletion by Law Enforcement
The ACLU has an app customized for about half the states, which is designed to record and transmit to the ACLU any encounter with law enforcement. Hands Up is another app that records video discretely and sends the video to your Dropbox and YouTube accounts. We like the fact that with Hands Up you retain control of the audio and video, and you have the choice as to whether to disclose the existence of it. Not all video may be helpful to your cause.
D. Searches of Your Phone; Deletion of Photos
Police generally have no right whatsoever to look at your phone. The Supreme Court has ruled that police may not search your cell phone when they arrest you unless they get a warrant. It is possible that courts may approve the temporary warrantless seizure of a camera or phone in certain extreme “exigent” circumstances such as where necessary to save a life, or where police have a reasonable, good-faith belief that doing so is necessary to prevent the destruction of evidence of a crime while they seek a warrant.
The police may not delete video or photos under any circumstance; doing so violates the 4th Amendment. You should never comply with a request that you do so. Your best protection is to use an app to upload videos and photos real time to secure servers.
E. A Note on Recording Audio.
With regards to videotaping, there is an important legal distinction between a visual photographic record (fully protected) and the audio portion of a videotape, which some states have tried to regulate under state wiretapping laws. The ACLU provide guidance on this issue, and suggests that nearly always making audio recordings of the police is legal.
Ii. The Law of Stop, Frisks and Searches
The police have limited power to require you to interact when them, and even more limited power to lay their hands on your or to search you, your house or car. The first rule of dealing with law enforcement is to make the interaction as limited as possible by understanding when you can walk away, what will give rise to the police having the power to lay hands on you and what can result in the police doing a detail search of your person.
A. "Justified Stop"
If interaction with law enforcement can be avoided, avoid it.
The police may legally stop you only if you are exhibiting the following factors (a "justified stop"):
- You appear not to fit the time or place.
- You match the description on a "wanted" flyer.
- You act strangely, or are emotional, angry, fearful, or intoxicated.
- You are loitering, or looking for something.
- You are running away or engaging in furtive movements.
- You are present in a crime scene area.
- You are present in a high-crime area (not this is sufficient by itself or with loitering).
If a police officer stops you, you probably have the right to walk away. So the first thing to do is to politely inform the officer that you would like to leave and ask if you are legally free to do so. Or better yet use the police technique in your word choice by assuming the outcome you want in your language: "Officer, I'd prefer to leave, I assume I am free to so, right?" or "Officer, I am going to leave now, ok?"
Unless the officer clearly communicates you are not free to leave, you may walk away. It is very possible the officer will not directly answer the question, but instead ask you additional questions. You should not answer any questions, and instead repeat you own question. If the officer again does not clearly communicate that you are being detained, inform the officer that you are leaving and only stay if the officer at any time clearly communicates you are required to do so.
From a practical point of view, you may be able to avoid the formality of the type of interaction described above. For example, you may be walking by law enforcement at a concert and they may say "Hey you guys, come over here, we have a few questions." You may simply continue walking and respond "Sorry, we do not want to miss the show." If the interaction continues, you may then escalate by saying, "Officer, I don't want to be rude but I assume you are not legally detaining me, so I am going to go see the show." Now you are into the type of more formal testing the waters as to whether you are being subject to a "justified stop", and the officer will most certainly understand your intention in your wording. As often as not, this friendly, but firm banter will end the interaction.
Remember, if the stop is not justified, anything that happens after the stop is not admisable against you. Therefore you want a very clear record that you did not consent to stop. In practice, the police will always suggest in court a pretext for stopping you (the suspects appeared nervous, intoxicated, etc.) But you are often going to be able to simply avoid the encounter, and in the worst case you are building a step by step defense in the event that you are arrested.
To this end, it's helpful to consider the most common justifications for a stop: you are acting strangely (typically acting nervously), have engaged in "furtive movements" (behaving stealthy) or are loitering. It is important to know these factors, and if law enforcement has told you that you are not free to leave, ask them under what grounds do they consider this a justified stop, and point out that you do not meet any of the conditions for a justified stop, to the extent you can do so. Recite as many as you can. Note, if you are overly intoxicated, and the officer identifies this as a factor, you may be best served to simply respectfully wait until the encounter ends, being cautious not to become emotional or nervous.
A note about DUI checkpoints. Perhaps surprisingly, the Supreme Court has ruled in favor of DUI sobriety checkpoints, applying a balancing test. Being stopped by the police is a "seizure" under the 4th Amendment, however, the Court found that under a balancing test, delaying a driver for a very brief period involves a very small intrusion, while advancing a significant state interest in preventing DUI's. Some states have determined searches to not comply with applicable law, and in those states you won't find a DUI checkpoint (here's a state by state analysis). Note, this decision in absolutely no way allows the police to stop you without justification in other contexts.
A note about DUI checkpoints. Perhaps surprisingly, the Supreme Court has ruled in favor of DUI sobriety checkpoints, applying a balancing test. Being stopped by the police is a "seizure" under the 4th Amendment, however, the Court found that under a balancing test, delaying a driver for a very brief period involves a very small intrusion, while advancing a significant state interest in preventing DUI's. Some states have determined searches to not comply with applicable law, and in those states you won't find a DUI checkpoint (here's a state by state analysis). If you are stopped at a DUI checkpoint, we likely have no obligation to interact with the police in any manner whatsoever other than to provide your driver's license and registration. However, our goal in the interaction is to do nothing to give the officer probable cause to extend the interaction. Our approach is to always have our registration close at hand so any traffic stop will go smoothly. When stopped at a DUI checkpoint, we roll down our windows half way, have our driver's license and registration ready to produce if requested, and engage in what should be a very brief exchange of words. We absolutely never drive intoxicated. We absolutely never have anything in plain view that would give rise to a search of our vehicles. As a result, the most pragmatic approach for us is to engage in the minimal interaction and be on our way. However, as always, we never consent to any search or waive any right in the encounter. We would never use the approach of placing our identification and registration in a bag and hold in through the window, as we suspect this increases the odds of creating probable cause that could lead to unwanted interactions. Keep it short. Keep it polite. And never waive a right.
B. A protective "frisk"
If you are subject to a "justified stop", the officer may have a right to frisk you. Legally, there is a difference between a "frisk" and a "search". If you have been subject to a justified stop you may be subject to a "protective frisk" (also known as a "protective pat down", which is a light pat down of your outer clothing designed solely for the protection of the officers.
A frisk is only permitted if an officer has a reasonable suspicion that you may be armed and dangerous. While a frisk may only be of a nature to search for weapons, once something that appears to be contraband or appears to be a weapon is discovered, the police may remove it. One of the best ways to understand the protective frisk (also known as a "Terry Frisk") is to read articles written for the benefit of law enforcement agents. An excellent overview can be found here with a good summary here.
An officer will almost always request permission to pat you down, typically by saying something like "I'm going to pat you down for your safety and mine, ok?". The answer should be, "No officer, I do not consent to a protective frisk. And I assure you that I present to no risk to you." If you do not have any weapons on you, you are well advised to say "No officer, I do not consent to a protective frisk. And I assure you that I am neither armed nor dangerous, and therefore there is no need nor legal justification for a frisk." This language signals that you understand what a protective frisk is, and the legal threshold for one to be authorized under law.
Note, if the officer then communicates that he is going to frisk you, absolutely comply, but remind the officer that you are complying but not consenting to the frisk.
C. Searches of your Person
Unlike a "protective frisk", a search of your person, car, or home may only occur following "probable cause" to conduct the search..
When applied to searches, probable cause exists "where the facts and circumstances within the officers' knowledge, and of which they have reasonably trustworthy information, are sufficient in themselves to warrant a belief by a man of reasonable caution that a crime is being committed."
Once probable cause exists, the officer may do a detailed search of your person, including removing outer clothing emptying pockets, opening your mouth, reviewing the contents of your wallet, etc.
If you are observed doing any action with would allow the officer to arrest you, or there is any evidence of a crime in plain view of the officer, there likely is probable cause to search you. Short of that, an officer likely does not have probable cause.
Again, if an officer asks to search you, politely decline.
D. Searches of Your Home or Car
The police may do a search of your home or car without your consent only if any of the following are true:
1. They obtain a warrant to do so from a judge. A search warrant requires: (1) the warrant be filed in good faith by a law enforcement officer; (2) the warrant be based on reliable information showing probable cause to search; and (3) the warrant must be issued by a neutral and detached magistrate; and (4) the warrant must state specifically the place to be searched and the items to be seized.
2. Consent. Even if you do not to consent to a search, the police may lawfully search the premise if any other person who is in control of the property consents to the search. For example, parents or roommates may consent to a search, and property found during that search will be admissible. Note, however, if you are physically present and object to the search, even if your roommate has consented, the police may not search the premise without a warrant or without meeting another criteria for a warrantless search.
3. Plain View. If a police officer sees contraband or evidence of a crime that is clearly visible, that object may be lawfully seized and used as evidence and may be the basis for a full search of your car or home.
4. Search Incident to Arrest. If you are being arrested in your house or car, police officers may search for weapons or other accomplices to protect their safety (known as a "protective sweep"), or they may otherwise search to prevent the destruction of evidence.
5. Exigent Circumstances. This exception refers to emergency situations where the process of getting a valid search warrant could compromise public safety or could lead to a loss of evidence. This encompasses instances of "hot pursuit" in which a suspect is about to escape.
F. Providing Identification
Do you need to provide your name or other identifying information to the police? If you are driving, every state requires you to produce your driver's license upon request. If you are not driving, some states require you to provide your name, address and birthdate. You should do a quick Google search to understand your rights in this regard. For example, in California you are not required to provide ID if you are not driving 
If you are uncertain of your rights, you may pull out your identification, place it face down in the palm of your hands, and tell the officer, "I do not consent providing my identification. However, if and only if I am legally required to provide this information, my identification is here. "
An important note: from a practical consideration, we will always provide identification to the police upon request if there has been a justified stop. Our cost benefit analysis suggests that police will likely view your refusal to provide identification as indicating you are likely subject to an arrest warrant. As a result we believe they are far more likely to find a reason or pretext to search or arrest you. Therefore, if (and only if) we are subject to a "justified stop" we will politely provide our identification.
For those who want to dig deeper, this guidance gives more detailed legal analysis and citations for the topics discussed here.
III. Practical Considerations
The best way to stay out of trouble with the law is to always obey it. The second best way is to "do no harm". Law enforcement is most likely to target those that are causing some type of social harm.
When attending public events, common sense will typically keep a person out of legal trouble.
1. Never drive intoxicated and avoid appearances of public intoxication.
2. Never violate any law while in the possession of a controlled substance. Drive the speed limit, do not have a broken tail light.
3. Never agree to be frisked or searched. Communicate clearly your refusal to be searched. Note, the police may have the legal right to search you and you should comply with any frisk or search the police insist upon. Forcibly resisting the police is virtually never legally permitted, and always a bad idea.
4. Be polite to law enforcement, but never waive any rights. Be very clear that you do not consent to a search. If asked any questions such as "would you mind if....", always respond clearly, "Yes, I do not want to do so." If you are told to do something by law enforcement, comply after confirming the law enforcement officer is legally requiring your action. "Please step out of the car." "Officer, I would prefer not to do so, but will comply with the request if you tell me I have no choice but to do so".
5. When declining a search, you may be well served to explain "Officer, I have nothing to hide. However, I believe strongly in the individual right to privacy and therefore do not consent to a search". Legally this serves a purpose: at all costs you do not want to give the officer probable cause to search you. Acting nervously is recognized as an indicia of illegal activity and may give rise to, at a minimum, the right for the officer to do a protective pat down. By explaining calmly your rational to avoid a search, you are building a transcript of a calm individual. As a side note, having interacted with many members of law enforcement, you are unlikely to provoke a negative reaction if you politely insist on honoring your rights. Moreover, by knowing your rights you are sending a powerful signal to law enforcement about your ability to protect your own interests.
6. Understand that when entering a private venue you may legally be required to consent to a search as a condition to entry. Private security is not subject to the same restrictions as public law enforcement. And any illegal materials found during such search may be turned over to public law enforcement and by fully admisable as evidence against you.
7. Ensure that you and all members of your group are safe. If you need medical intervention, you are likely to also encounter law enforcement. Watch each other's backs. You are less likely to be confronted by security or law enforcement if your group is cohesive and acting with courtesy.
A final reminder. Never believe law enforcement is not entitled to lie to you. It is entirely legal for a member of the law enforcement community to lie about their profession, their relationships, their drug use, etc. This is done routinely, including law enforcement using bona fide credentials of legitimate businesses, such as business cards or employee badges.
Don't think you can recognize undercover police. You can't. The attractive woman with pasties and a tutu may be a cop. The guy walking on stilts may be a cop. This is the way it works.