Do I need a nondisclosure agreement or confidentiality agreement before discussing my invention with a patent attorney?

Inventors should use a nondisclosure agreement (NDA), sometimes called a confidentiality agreement or confidential disclosure agreement (CDA), before discussing their invention with most other people. When I say “most” other people, there are some people you can disclose your invention to without such an agreement.
For example, you may not need a nondisclosure agreement to disclose your invention to a business partner, if the invention is going to be owned by the business. Likewise, disclosing your invention to very close family (for example, your husband or wife) probably would not be considered a public disclosure of your invention.
Inventors should use a nondisclosure agreement before disclosing their invention to potential investors, manufacturing companies, product designers, and development companies, if the inventor has not yet filed a patent application. Of course, it is best to file a patent application first, before making any disclosures of an invention.
This raises the initial question – “do you need a nondisclosure agreement or NDA to show your invention to a patent attorney.” In most cases, a patent attorney is going to be bound by the duty of confidentiality without a formal nondisclosure agreement.
But inventors should never discuss their invention in detail with anyone, even a patent attorney, until there is a formal attorney-client relationship. Many patent attorneys require a signed Fee Agreement before forming an attorney-client relationship with anyone.
It’s simply not necessary to go into detail about your invention until you have hired a patent attorney. The patent attorney can check for conflicts of interest and give inventors general information based on a high-level description of the invention. For example, you can describe your invention simply as relating to a child’s toy, a tool, an auto part, and kitchen utensil, and so forth, without saying exactly what the invention is and how it works.
Inventors should never talk in detail about or send any information, for example in an email, about an invention to a patent attorney until the patent attorney has agreed that you are a client – again having signed the Fee Agreement. That way, there can be no misunderstanding by the patent attorney that you expect details of your invention to remain confidential.