The answer to this turns on 35 USC § 102(a), which reads:
A person shall be entitled to a patent unless—
(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention; or
(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention.
Section 102(a)(1) covers the typical scenario of a publication. When a patent application (or any document at all) is published, it becomes §102(a)(1) prior art as of its publication date. This section therefore does not apply to unpublished applications (whether provisional or non-provisional).
Section 102(a)(2) relates more to double patenting. The three requirements are:
- the claimed invention was described in an issued patent or an application published under §122; AND
- the patent or application names another inventor; AND
- the patent or application was effectively filed before the effective filing date of the claimed invention.
An unpublished provisional fails at the first hurdle: it is neither an issued patent nor an published application. It therefore cannot be regarded as prior art until it is published.
How about dropped but published provisionals for patents with priority date between filing and publishing of said provisional?
A published provisional application is prior art under §102(a)(1) (like any published document), as of its date of publication. However, it is still not §102(a)(2) prior art.
This is because a provisional application is never published under §122 (and therefore will never meet the first requirement above). This is clear from §122(2)(A) which provides:
An application shall not be published if that application is— ... (iii) a provisional application filed under section 111(b)
What about non-provisionals?
Once they are published (and not before, per the first requirement above), non-provisionals are §102(a)(2) prior art. However, they are prior art as of the effective filing date (not the publication date).
This has an interesting dynamic when paired with a provisional. A published non-provisional which claims the benefit of the provisional is §102(a)(2) prior art as of the date that the provisional was filed. This is because the effective filing date of the non-provisional is the provisional's filing date.
