"In China, there is no doctrine preventing an
applicant from obtaining multiple patents for obvious variants,
patentably indistinct subject matter, or incremental improvements,
so long as the claims are not identical in scope." - Michael Huang
Double patenting doctrine worldwide builds on the principle that
an inventor is entitled to only one patent for each invention.
Obtaining multiple patents on the same invention could circumvent
this principle by extending exclusivity beyond statutory
expiry.
On its face, the principle is simple enough. In practice,
"same invention" is not a simple concept at all:
variations in local rules and interpretations-including different
approaches to issues such as claim scope and construction;
obviousness (in the "patentably distinct" context);
amendments limits; and shifting claim sets when multi-application
families exist-converge to create a panoply of double patenting
regimes internationally. The resultant complexity can be
