How does a prior art reference disclosing a range overlap with a claimed range affect patentability?

This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice.

When a prior art reference discloses a range that overlaps with a claimed range, it can affect patentability in the following ways:

• If the prior art range overlaps or lies inside the claimed range, it may establish a prima facie case of obviousness.
• The overlapping ranges create an expectation that the claimed range will have similar properties to the prior art range.
• To overcome this rejection, the applicant must demonstrate that the claimed range is critical or produces unexpected results.

As stated in MPEP 2144.05(I): “In the case where the claimed ranges ‘overlap or lie inside ranges disclosed by the prior art’ a prima facie case of obviousness exists.”