NOTE: This order is nonprecedential.

United States Court of Appeals 

for the Federal Circuit ______________________

In re: DMF, INC., a California corporation,

Petitioner

______________________

2021-153

______________________

On Petition for Writ of Mandamus to the United States 

District Court for the Central District of California in No. 

2:18-cv-07090-CAS-GJS, Senior Judge Christina A. 

Snyder.

______________________

ON PETITION

______________________

Before LOURIE, BRYSON, and TARANTO, Circuit Judges.

PER CURIAM.

O R D E R

DMF, Inc. petitions for a writ of mandamus challenging the district court’s ruling that AMP Plus, Inc., dba 

ELCO Lighting (“ELCO”) was not statutorily estopped

from raising a particular ground of invalidity. ELCO opposes. DMF replies.

This petition concerns the scope of statutory estoppel 

under 35 U.S.C. § 315(e)(2). A petitioner in an inter partes

review may request to cancel as unpatentable one or more 

claims of a patent only “on the basis of prior art consisting 

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2 IN RE: DMF, INC.

of patents or printed publications.” 35 U.S.C. § 311(b). Section 315(e)(2) provides that the “petitioner in an inter 

partes review of a claim in a patent . . . may not assert . . .

in a civil action . . . that the claim is invalid on any ground 

that the petitioner raised or reasonably could have raised 

during that inter partes review.” 

DMF is the owner of U.S. Patent No. 9,964,266 (“the 

’266 patent”) directed to certain compact recessed lighting 

products. In August 2018, DMF filed this suit in the

United States District Court for the Central District of California, alleging ELCO infringes various claims of the ’266 

patent. ELCO raised several invalidity grounds, including 

arguments premised on a boating light product sold under 

the name Hatteras that had been featured in a product catalog published in 2011 by Imtra Marine Lighting. 

In May 2019, ELCO petitioned for inter partes review

of the ’266 patent. The Patent Trial and Appeal Board instituted review of all the challenged claims on three 

grounds based on the Imtra 2011 catalog either alone or in 

combination with other references. In its final written decision, the Board held that ELCO had not proved that all 

the challenged claims were unpatentable. Following the 

Board’s decision, DMF moved the district court under 

§ 315(e)(2) to bar ELCO from asserting invalidity in the litigation based on the Hatteras product itself. 

The parties agreed that section 315(e)(2) estoppel was 

to be assessed based on whether there was a substantive 

difference between the physical Hatteras product relied 

upon by ELCO in this case and the description of the product in the 2011 Imtra catalog germane to the invalidity dispute. See Appx6; Appx112 (DMF’s reply brief in support of 

motion) (“The parties appear to agree that courts in this 

District and elsewhere require that—as stated in ELCO’s 

own Opp. at 7—there be some substantive difference between the product and the printed prior art that is germane 

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IN RE: DMF, INC. 3

to the invalidity dispute at hand” (internal quotation 

marks and emphasis omitted)). 

Applying that standard, the district court denied the 

motion. Relying on DMF’s own prior argument that the 

Imtra reference could not anticipate the claims because 

ELCO’s invalidity contentions mixed and matched components from various products disclosed in the catalog, the 

district court found that anticipation arguments based 

solely on the Hatteras product were substantively, germanely different. The court added that ELCO was relying 

on the physical product as a reference for various limitations because the descriptions in the Imtra catalog did not 

disclose all of the Hatteras product’s features. 

Mandamus is “reserved for extraordinary situations.” 

Gulfstream Aerospace Corp. v. Mayacamas Corp., 485 U.S. 

271, 289 (1988) (citation omitted). Under the well-established standard for obtaining such relief, the petitioner 

must: (1) show it does not have any other method of obtaining relief; (2) show that it has a clear and indisputable legal 

right; and (3) convince the court that the “writ is appropriate under the circumstances.” Cheney v. U.S. Dist. Ct. for 

D.C., 542 U.S. 367, 380–81 (2004) (citation omitted). We 

cannot say that DMF has satisfied that standard. 

DMF has not shown that a post-judgment appeal is an 

inadequate remedy for asserting a statutory estoppel argument. See In re Verinata Health, Inc., No. 2017-109, 2017 

WL 1422489, at *2 (Fed. Cir. Mar. 9, 2017). Nor has DMF 

shown that it has a clear and indisputable right to relief. 

Significantly, DMF agreed to the legal standard for assessing statutory estoppel applied by the district court. In 

essence, DMF is challenging the district court’s application 

of that standard and its findings that ELCO was not judicially estopped from raising its arguments based on actions 

before the Patent Office. We are not convinced that DMF 

has met its heavy burden of showing that the district 

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4 IN RE: DMF, INC.

court’s rulings in these regards are clearly and indisputably erroneous. 

Accordingly,

IT IS ORDERED THAT:

The petition is denied.

September 09, 2021 

Date

FOR THE COURT

/s/ Peter R. Marksteiner

Peter R. Marksteiner

Clerk of Court

s29

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