We aren’t lawyers but this is our best understanding as plain-old US citizens.
Dumpster diving is legal in the United States except where prohibited by local regulation. According to a 1988 Supreme Court Ruling (California vs. Greenwood), when a person throws something out, that item is now the public domain. Here is some language from that ruling: “It is common knowledge that plastic garbage bags left on or at the side of a public street are readily accessible to animals, children, scavengers, snoops, and other members of the public.”
However, if a dumpster is against a building or inside a fenced enclosure marked “No Trespassing,” you could be questioned, ticketed or even arrested by the police. Other law-enforcement tactics to discourage dumpster diving include:
– to ticket or arrest for littering (hence the legal as well as common courtesy reason to leave a trash area neater than you found it!);
– to ticket or arrest for disorderly conduct, if you are blocking a sidewalk or generally creating a ruckus while dumpster diving, or refuse to leave an area when requested to do so.
Unless a town or city has specifically made dumpster diving illegal, generally the police will not come unless called by a store manager or property owner. In our experience, this is yet another good reason to be courteous with any store employee (or resident with a dumpster) who questions the dumpster diving in progress, and to use common sense about how long an individual or group stays at any one trash location. If anyone asks you to leave, consider doing so, even if the law is on your side– there are plenty of other wasted resources to be found.
Good Samaritan Law: No Excuses for Not Donating
Store managers will claim that food in their dumpster cannot legally be consumed by humans, or that they cannot donate or give it away. This is either ignorance or lies. If you have the patience to educate, you may want to bring up the Good Samaritan Food Donation Act that has has been the law since the 1990s.
Some people suggest telling store managers you are collecting food to feed livestock or for a compost pile and if you don’t want to make a political point on the waste this will usually work. Some managers will even tell you when certain items are discarded (ie; produce), and encourage you to come get them. The main thing that food stores are worried about is¬† someone getting sick from what they throw away, and then suing them.
There is backlash in a number of communities on the issue of “theft” of recyclables from city recycling bins. Metal can often be sold at prices that make scavenging aluminum (especially cans with a fixed deposit), old appliances, and even power cords a viable cottage industry. A number of cities now have laws against this kind of dumpster diving with a vehicle. Most cities will not harass the small-scale scavenger with a granny cart or bicycle.
“Warning, do not play on in or around dumpster” — such signs are for the protection of the people who own or rent the dumpsters, in case someone gets hurt, to avoid liability.
Wikipedia on dumpster legality Includes some info on the legal situation in Europe and Canada.