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Federal Circuit clarifies limited exception to the presumption that ‘consisting of’ is a closed term

Elizabeth Crompton

Elizabeth Crompton
Haynes and Boone, LLP

In the case of a claim directed to a composition “consisting of” substances selected from a Markush group, when is the presence of an unclaimed ingredient sufficiently unrelated to the invention to preclude infringement?  The Federal Circuit recently addressed this question in Shire Dev., LLC v. Watson Pharm., Inc., No. 2016-1785 (Fed. Cir. February 10, 2017).  The Federal Circuit reversed the district court’s finding of infringement because the accused product did not satisfy the claimed Markush group requirements.  Shire, No. 2016-1785 at 2.  Specifically, the Court found that the accused product containing an ingredient not listed in the claimed Markush group did not infringe where that additional ingredient structurally and functionally related to the invention.  Id. at 7-9.

The asserted claims of U.S. Patent No. 6,773,720 require a controlled-release oral pharmaceutical composition including a specific active ingredient; an inner, lipophilic matrix; an outer, hydrophilic matrix; and other excipients.  Id. at 2.  In full, claim 1 reads:

  1. Controlled-release oral pharmaceutical compositions containing as an active ingredient 5-amino-salicylic acid, comprising:
  2. a) an inner lipophilic matrix consisting of substances selected from the group consisting of unsaturated and/or hydrogenated fatty acid, salts, esters or amides thereof, fatty acid mono-, di- or triglycerids, waxes, ceramides, and cholesterol derivatives with melting points below 90° C., and wherein the active ingredient is dispersed both in said the lipophilic matrix and in the hydrophilic matrix;
  3. b) an outer hydrophilic matrix wherein the lipophilic matrix is dispersed, and said outer hydrophilic matrix consists of compounds selected from the group consisting of polymers or copolymers of acrylic or methacrylic acid, alkylvinyl polymers, hydroxyalkyl celluloses, carboxyalkyl celluloses, polysaccharides, dextrins, pectins, starches and derivatives, alginic acid, and natural or synthetic gums;
  4. c) optionally other excipients;

wherein the active ingredient is present in an amount of 80 to 95% by weight of the total composition, and wherein the active ingredient is dispersed both in the lipophilic matrix and in the hydrophilic matrix.

U.S. Patent No. 6,773,720, at col. 6, ll. 7-31.

Previously, as part of the long history of this dispute, the Federal Circuit held that the claimed matrices were “defined by mutually exclusive spatial characteristics—one inner, one outer—and mutually exclusive compositional characteristics—one hydrophilic, one lipophilic.”  Shire, No. 2016-1785 at 4 (citing Shire Dev., LLC v. Watson Pharm., Inc., 787 F.3d 1359, 1366 (Fed. Cir. 2005) (2015 Decision), remanded by 135 S. Ct. 1174 (2015) granting cert to and vacating 746 F.3d 1326 (Fed. Cir. 2014)).  Thus, the Federal Circuit explained, the matrices, not just the ingredients thereof, must exhibit the appropriate characteristic matrix compositions, limited by the ingredients in each Markush group.  Id.  The parties stipulated to the definitions of lipophilic (“poor affinity towards aqueous fluids”) and hydrophilic (“having an affinity to water”), and the Federal Circuit found that the lipophilic and hydrophilic matrices had the relevant properties such that the hydrophilic matrix readily dissolved in water, and the lipophilic matrix resisted dissolving in water.  Id. at 2-3 (citing 2015 Decision, 787 F.3d at 1362 n.1, 1365; Shire Dev. LLC v. Watson Pharm., Inc., No. 12-60862-CIV, 2016 WL 1258885, at *6 (S.D. Fla. Mar. 28, 2016) (2016 Trial Decision)).

The issue was whether the claims were infringed by defendants’ product with an outer hydrophilic matrix containing magnesium stearate, a lipophilic ingredient used as a lubricant.  Id. at 6-7.  The district court held that the defendants’ product did infringe, finding that the magnesium stearate did not drive the water affinity properties of the outer matrix.  Id. at 4-5 (citing 2016 Trial Decision, 2016 WL 1258885, at *4, *15).  The Federal Circuit disagreed with the district court’s conclusion.  Id. at 7-9.

As the Federal Circuit explained, claim 1 characterizes each matrix as “consisting of” or “consists of”, and defines each Markush group of matrix ingredients with “consisting of.” Id. at 5.  These terms create a strong presumption that the claim element cannot include ingredients not listed.  Id.  To overcome this presumption, the specification and prosecution history would have to unmistakably demonstrate that the term should be used in a different way.  Id.  Alternatively, there is also an exception to the “consisting of” presumption for “aspects unrelated to the invention.”  Id. at 6 (citing Norian Corp. v. Stryker Corp., 363 F.3d 1321, 1331 (Fed. Cir. 2004)).

The Federal Circuit analyzed Norian with regard to whether a component is “unrelated to the invention.”  In Norian, adding a spatula to a phosphate chemical kit for repairing teeth and bones did not avoid infringement of a claim to a kit consisting of the chemicals themselves, as the spatula had no interaction with the chemicals and was irrelevant to the invention.  Id. (citing Norian, 363 F.3d at 1331-1332).

The Federal Circuit then considered whether the magnesium stearate in the accused product was similarly irrelevant to the invention as the spatula was in NorianId. at 6-7.  The accused product’s hydrophilic matrix included magnesium stearate—a lipophilic ingredient.  Id. at 7.  According to the Federal Circuit, the invention was a multimatrix system that relies on the hydrophilic and lipophilic characteristics of the matrices to provide for the slow release of the active ingredient at the desired time.  Id.  As such, when the hydrophilic matrix interacts with digestive fluids, it swells and blocks the digestive fluids from reaching the inner lipophilic matrix, allowing the invention to pass through the digestive system until the outer matrix breaks apart and releases the inner lipophilic matrix.  Id.

Magnesium stearate in the accused product affects the characteristics of the hydrophilic matrix and the overall dissolution properties.  Id. at 7-8.  In particular, the district court found that magnesium stearate is lipophilic and exerts some lipophilic influence in the hydrophilic matrix.  Id. at 8 (citing 2016 Trial Decision, 2016 WL 1258885, at *11-12).  The district court found that even in small quantities, magnesium stearate could increase dissolution time.  Id. (citing 2016 Trial Decision, 2016 WL 1258885, at *11-12).

Thus, the Federal Circuit concluded that magnesium stearate retains its lipophilic character in the hydrophilic matrix and, therefore, structurally and functionally relates to the invention.  Id.  As such, the presence of magnesium stearate in the hydrophilic matrix avoids the “consisting of” limitation in claim 1(b).  Id.

The Federal Circuit also rejected the plaintiff’s argument that magnesium stearate is unrelated to the invention because it is not sufficiently lipophilic to render the hydrophilic matrix lipophilic.  Id.  As the Federal Circuit pointed out, Norian did not limit “related” to only components that “advance or are intended to advance a Markush group’s allegedly inventive elements.”  Id.  Requiring so would improperly equate “consisting of” with “comprising” or “consisting essentially of.”  Id. at 8-9.

The Federal Circuit also noted that examples including magnesium stearate in the extragranular space did not overcome the presumption that Markush groups are closed, as nothing in the specification or prosecution history changed the meaning of the term “consisting of,” and the plaintiff did not challenge the construction of that term.  Id. at 9.  .

This case provides a reminder to patent drafters that “consisting of” is a closed term.  Although a product including an unclaimed ingredient may still be found to infringe if the unclaimed ingredient has no connection with the claimed invention, any effect on the properties may preclude infringement.  If the drafter desires a more flexible construction so that the claims may include other ingredients, then “consisting essentially of” may be an alternative. From a litigation standpoint, when dealing with “consisting of” claims, consider whether an unclaimed ingredient has no connection to the invention (for patent owners) or has some effect on the properties of the invention (for accused infringers).

Elizabeth Crompton is an experienced trial attorney who uses her advanced education and experience to understand complex technical matters and help clients achieve their goals. Elizabeth concentrates on patent disputes before district courts and the Federal Circuit. She also counsels clients on infringement, validity and enforceability of patents, particularly in the chemical/biological and mechanical areas, including Hatch-Waxman, as well as design patents.

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