Hi Peter6, yes once information is in the public domain it can no longer be confidential information. This includes when you apply for a patent - you must make public disclosure of your inventions and so once you lodge a patent application your information is no longer confidential, so if you don't have a non disclosure agreement in place, there's pretty much nothing you can do.
There were 6 things outlined in the case of
Ansell Rubber Co Pty Ltd v Allied Rubber Industries Pty Ltd that are relevant to determining whether a trade secret is confidential;
- the extent to which information is known outside your business;
- the extent to which the information was known by others involved in your business (and the precautions you took to guard the secrecy of the information);
- the value of the information to you and to your competitors;
- the amount of effort or money expended by you in developing the information; and
- the ease or difficulty with which the information could be properly acquired or duplicated by others.
As I said earlier it will be up to a court to decide whether or not, based on these 6 factors, your inventions constitute confidential information. If you believe you have suffered significant loss as a result of the other company exploiting your ideas, speak with an IP lawyer about your prospects of suing.