If your idea has already been patented anywhere in the world, your invention is not original and therefore cannot be patented. A patent search report provides a list of existing and pending patents that are similar to yours. This can give you a better understanding as to whether your idea is novel and non-obvious, two of the three requirements to be eligible for a patent.
Patent searches vary by the amount of data that is searched through. A search of free patent databases such as from the US Patent Office website or Google Patents will only search through most US patents. However, even an international patent could be used by a patent examiner at the US Patent & Trademark Office (USPTO) to reject your patent application. As a result, it is important that a search includes international patents as well.
A professional performing a patent search will know how to identify only patents which are most relevant to an invention from the perspective of patent law. It is almost impossible to have a patent search come up with no results. This is because it is the responsibility of a searcher to find anything similar. For example, if you invented the bottle, a search report would identify a cup, a mug, a jug, maybe even a bucket. A professional patent search report needs to identify any related inventions that could possibly prevent your invention from being patented.
It is important to know that finding evidence of inventions similar to your own does not necessarily mean your invention cannot be patented. If your invention is uniquely different, it may be considered novel. In many circumstances, even adaptations of previous inventions can be patented if the adaptation is non-obvious. For example, Lemelson patented the camcorder but he did not invent the VCR or the camera. What is considered non-obvious is often very subjective. Lemelson was not granted a patent to his camcorder on his first patent application submission. His application required amendments and arguments from his patent professional before it was finally approved. Even if you think an existing invention is similar to yours, it may not be considered obvious in the world of patent law. Consult with a licensed patent professional before dismissing any idea.
A professional patent search report is a valuable resource to have before filing a patent application. Not only does it give you a higher degree of confidence towards filing your patent application, the knowledge gained can help you and your patent professional draft an effective application to meet your protection goals.