Can I Publish Photos of Kissing Couples?

Dear Rich: I'm a writer and photographer with a question about using candid street photos in a for-profit book. Let's say I'm writing a book about romance. During my travels, I take some candid shots of singles and couples. These people are flirting or holding hands in public. Or commuting on the subway or at cafes and pubs. (Always in public.) Can these photos be used inside an electronic or print book without compensation or a model release/waiver? I presume the law would be different if a photo was used on the cover of the book as that would require a model release. Is the law different if I'm publishing a "travelogue" instead of a book of stories? I'm interested in both U.S., European, and Japanese law as this project may take me overseas. If a flirting person is in public, the general rule in most countries is that you are free to take and publish an image. (Here are  the international consent requirements.) However, you would likely need permission if using the photo for commercial purposes -- that is, to sell something. (So, yes, you are correct that using an image on the cover might require permission -- although some kissing covers end up rewarding the subjects in other ways.) To avoid legal problems, the text that accompanies the photos should not defame your subjects (for example, implying one of the parties is a prostitute) or invade their privacy. (These laws may differ from country to country and state to state.) Other than these concerns, you should be fine using the images within a book whether fiction or travelogue ... unless of course, you trigger some kind of nonlegal reaction -- for example, revealing adultery like Google View or red light cameras.