In England, Germany, Austria, Sweden, Norway, Finland, Poland and I'm sure a few other European countries they have explicitly spelled out the right to wander in the woods, the freedom to roam, or what is called "Everyman's Right".

To summarize, as long as you're not harming anyone, picking endangered flowers, disturbing residents, etc., you have the right to cross over rural property and camp for a night. The law of course, varies from country to country.

http://en.wikipedia.org/wiki/Right_o...the_wilderness
http://www.pinetreedevelopment.net/s...lemansratt.php
http://www.ymparisto.fi/default.asp?...d=49256&lan=EN
http://www.maf.govt.nz/mafnet/rural-...utdoors-07.htm