Here is my understanding and basically what I was taught when I was in photography school (Brooks Institute of Photography Grad)
All of these following examples are perfectly acceptable and legal for you to photograph:
- crowded Times Square or city atmosphere
- people participating in a parade, demonstration, fair, or concert
- a couple holding hands, walking in the park at sunset
- students leaned over piles of books, studying at your local public library
- neighborhood goings-on, if taken from the public sidewalk
- a portrait of a woman, only okay if used in the sense of “editorial content.”
- an accident or event you stumbled upon (even with intention to sell to the media)
- public figureheads – president, governors, senators, famous people, shot from public property
If you are on public property: parks, sidewalks, the middle of downtown, libraries, you are allowed to photograph the environment, ambience and situational events as long as they are not government buildings, military property, or nuclear power plants. It is perfectly acceptable to photograph public bridges, and buildings (even if people tell you otherwise, such as “architectural copyright”), statues, public outdoor art, fountains, beaches, churches, etc. as long as you do so while on public property. Signage will usually not allow photography at TSA screen checkpoints, but officially it’s legal as long as it doesn’t interfere with safety.
Think about National Geographic magazine. They often photograph intimate images of people. Those images are created with the premise of sharing cultures, their people, their customs and those images are created in the context of editorial content (illustrating how people dress, they way they look, where they live, etc.). National Geographic does not need any special permissions to photograph or publish those images.