Filing an "Information Disclosure Statement" (an IDS) is critical in almost every patent application filed with the United States Patent and Trademark Office (USPTO). Very simply, an IDS is a list of literature that may be related to your patent application, including other patents and patent applications, websites, articles, advertisements, research publications, etc.
Of course, the first impulse is often: "why do I need to give the USPTO literature related to my application ... why can't they find it themselves?" There are two answers: 1) it is required by law, and 2) it actually strengthens your patent.
First, you are required by law to file any prior art that you, or others involved with your application, are aware of. This requirement is called an applicant's (and their counsel's) "duty of disclosure." It is required as part of the ‘exchange’ inventors make with the public in order to receive a period of exclusivity. The USPTO explains: "A patent by its very nature is affected with a public interest. The public interest is best served, and the most effective patent examination occurs when, at the time an application is being examined, the Office is aware of and evaluates the teachings of all information material to patentability. Each individual associated with the filing and prosecution of a patent application has a duty of candor and good faith in dealing with the Office, which includes a duty to disclose to the Office all information known to that individual to be material to patentability as defined in this section." (emphasis added).
An IDS is a straightforward method provided by Congress that allows applicants to submit any ‘art’ they may be aware of that could affect the patentability of your invention. Because using an IDS to submit all required information meets this “duty to disclose,” it helps streamline the process of fulfilling your legal requirements.
The duty to disclose to the patent office is a critical one. If it is determined that an applicant -- or their counsel -- has not properly fulfilled their duty to disclose, the patent application will be canceled if it has not issued, or rendered unenforceable if it has already been granted. Of course, this tends to make proper disclosure an appealing area of intense scrutiny if a competitor is seeking to invalidate your patent.
This has happened before, such as was the case in McKesson v. Bridge Medical, when a patent was found unenforceable because a patent attorney did not disclose an Office action found to be material to patentability.
Second, the more potential prior art that is considered when your patent application is being examined, the stronger any resulting patent is. There is a presumption of validity of an issued patent, particularly in relation to prior art already considered by an Examiner during examination of the application. Thus, the more information that is submitted, the more can be considered by the Examiner, making it potentially that much more difficult for a challenger to overcome the presumption of validity.
Additionally, the law provides little incentive for not filing an IDS, because a reference submitted in an IDS is not an admission of prior art. Even if you're not sure if a reference would be prior art, but think a reasonable person would consider it helpful for an Examiner to look at while examining the application, it's typically good to disclose anything you're unsure about. If anything, most likely, it will only help strengthen your patent.
Both you as an applicant, and everyone involved with your patent application — other inventors, your patent counsel, etc. — should diligently submit any references that might be considered "material to patentability." These references include previous disclosures, previous office actions from the USPTO or foreign patent offices, trade shows, sale offers, information regarding enablement, and much more. A good rule of thumb is to always err on the side of disclosure for two reasons: it's the law, and it should actually help strengthen your resulting patent(s).