Have you ever sat in a restaurant booth discussing an idea you had with a friend or family member? Then, suddenly, that idea is a reality a few months later? This is precisely why authors, artists, and songwriters refuse to discuss their work with anyone until it is a concrete thing. Anyone overhearing your ideas or hearing about your creations can take them, but you may be wondering if you can sue. You can consult an intellectual property lawyer, but the following is probably what the lawyer may tell you.
Ideas from the Ether
The problem with ideas is that anyone can claim them. Even if you heard someone else's idea or pulled it from your subconscious after hearing about it somewhere and forgetting it, you are not considered to be taking someone else's idea, anymore than someone else can take your ideas. As long as ideas are only talked about, they are free for anyone to take, which is why so many creative people do not discuss their creations. If you talked about an idea you had for a product out loud and in public, and suddenly someone else beat you to it, guess what? It will be very difficult to prove it was yours.
Ideas on Paper or in Development
On the other hand, if you drew out your ideas and had someone you trust see the drawings or designs (either on paper or in a computer program), you may stake a valid claim. You have both the designs/drawings you made and a witness to their creation already ready before someone else made it a reality. If your idea is already in development and is currently being turned into a real product, then your claim has even more strength. With this proof in hand, you can sue the party that stole your work and your idea.
If you can and will make a claim against the person or company that has stolen your idea/product, be absolutely sure they did not come up with it before you. You have to prove that yours came first, a sort of "chicken and the egg" situation. Your intellectual property lawyer can do the necessary research with you to verify that your idea came first, and therefore prove that you are entitled to all rights and profits on the idea, design, and product currently on the market. It will not be an easy process, but if you clearly have a valid claim, you should sue.