Legal issues can arise from street photography activities. One potential hazard is trespass, whether intentional or not. Abandoned premises, demolition site and run-down areas may seem attractive from a photographic point of view but may also be protected or patrolled by private security companies or the local police. If challenged it is best to explain honestly what you are doing, although the security guards may be suspicious or just not believe you. Many people do not understand why anyone might want to photograph run-down areas. If you are asked to leave the premises, do so without argument. It really is easier than getting arrested!
Another potential legal problem can arise when pictures of certain buildings are published. It is important to understand the law in the relevant country. In the UK, for example, it is legal to photograph buildings and property provided the photographer remains on public land. Step on to privately-owned land and the permission of the owner is required. However, that is not the end of the story. A house owner whose name or address is clearly visible in a photograph may claim that publishing an image of his or her property invites criminal attention, and may consequently sue the photographer.
In most cases images taken from public areas, such as roads, footpaths and pavements, are legal provided they are used for private or non-commercial public purposes only. Pictures used for commercial purposes, for instance advertising a particular product, may only be used legally when a property release has been signed by the relevant parties.
Always bear in mind that in other countries and jurisdictions the law may be significantly different. In Paris, France, almost everyone takes photographs of the Eiffel Tower. However in 2003 a new display lighting system was installed on the tower and protected by copyright. Night-time images of the tower can therefore not now be published without the permission of the company concerned. It may be considered crazy, but this is the current legal situation!