Take a look at this article http://www.wired.com/2013/08/bitocoin_anonymity/ "Whoever pulled off the Betcoin heist hasn’t been caught, but once stolen Bitcoins pass into an exchange or they’re used in some other transaction, law enforcement has many ways of tracking down a culprit. You need to provide proof of identity to trade on Mt. Gox. Exchanges can also hand over information such as IP addresses and bank account numbers to investigators.

The feds are still concerned about such thefts, and about Bitcoin’s role in money laundering and illicit commerce. Last year, a leaked FBI Intelligence Assessment warned that the private nature of the digital currency could make it hard for law enforcement to track criminals. You don’t need any ID to create a Bitcoin wallet, but the Bitcoin network is built in a way that can make it awfully difficult for criminals to spend the digital currency once they steal it." stealing bitcoin is just as illegal as stealing real world money.

yeah, it is pretty obvious that stealing literally anything is illegal, in my opinion it is better to avoid taking something from another person without the permission at all

Okay, how about the following situation. You stumble upon a wallet that has 50 BTC in it and hasn't been used for years, forgotten. Would you still destroy the seed?

If its illegal or legal its irrelevant.

Ultimately, what prevents us from pursuing illegal activities its the accordance or not to our moral being, not its legality.

Is it morally questionable to use those  50BTC?

Yes, if your gonna spend it on a gold platted iphone.

No, if your gonna feed 20 000 starving kids with it.

Ask someone else and you may have a different answer. There are no clear answers when we enter into the human soul.

I don't think it's illegal and even if it is, how would you enforce it? It is unethical I'll say that much. The odds of this happening is so unlikely though directory.io illustrates this problem pretty accurately

You guys need to learn how to read the thread, not just the title. Please go back and read it before you say thinks like "obviously yes it r illegal m8". I know stealing Bitcoin is illegal but that wasn't my full question, as I wouldn't be able to fit it into the title in such a way it would make sense. So actually read the thread fully before you post.

Yeah you the topics says it already, stealing Bitcoin is illegal because it does not belong to you when you are stealing it.
But because it is online and Bitcoin is anonymous I am not sure if they are able to prevent it.

What would make him the owner though? I generated the address, I had no intention of stealing Bitcoin but now because of the Bitcoin Core application I own an address with BTC in it. Not sure how that's stealing. Others have already posted a better answer saying it's not legal or illegal since there are no laws governing it. If I breach a website and steal private keys that is illegal I know, but if I generate an address with BTC in it who knows the person who deposited that BTC didn't generate the address after another person already had, making him not the owner. The owner is not decided by who generates the address first. All you can do is try to be secure as possible.

Just have the word "stealing" confirms it; taking something from someone without their permission or consent. Is stealing illegal? Ofcourse it is; though its may be hard to track down Bitcoin scammers and thieves its is by no way legal to do so. I bet you wouldnt want your money just taken by someone for free surely you would want it back right?