If I have the slightest doubt that something I am gonna to do is legal in the country I just ask some local people about it. Depending on the activity I even ask a police man.
Plus I read a bit about any country I am visiting in a guide book. If there are certain laws that are very different from the ‘Western World’ they are usually mentioned in guide books.
That should cover you for most things you do as a tourist.
The ministries of foreign affairs of many countries offer travel advice on their websites.
http://www.fco.gov.uk/en/travel-and-living-abroad/travel-advice-by-country/
http://www.voyage.gc.ca/countries_pays/updates_mise-a-jour-eng.asp
http://www.diplomatie.gouv.fr/fr/conseils-aux-voyageurs_909/index.html
http://travel.state.gov/travel/cis_pa_tw/cis/cis_4965.html
http://www.smartraveller.gov.au/zw-cgi/view/Advice/Index
etc …
These sites are well known for their advice on safety and security and entry requirements. Nevertheless, they also have sections on “local laws and customs”. Look for instance what the FCO says about Singapore.
Credit:stackoverflow.com‘