For patent infringement defendants filing an Inter Partes Review (“IPR”) petition to challenge the validity of the patents asserted against them has become popular, largely because of the high rate of patents rendered invalid as a result of the petitions. Thus, knowing when to file an IPR petition is crucial.
In a common scenario, a patent owner sues defendants X and Y in a district court for infringing its patent 123. A few months into the district court litigation, X files an IPR petition with the Board, challenging the validity of patent 123. Six months later, the Board institutes X’s petition. Y, knowing the Board’s reputation as being a “death squad” for patents, has been thinking about filing an IPR petition but has not done so. Now, X’s petition is instituted, can Y file an IPR petition? Meanwhile, in light of the institution decision, the patent owner asserts additional claims, can X file another IPR petition?
To evaluate options for X and Y, this article reviews the relevant IPR rules, particularly the joinder rule, and how the Patent Trail and Appeal Board (“Board”) has interpreted these rules. This article also discusses strategies to avoid potential pitfalls.
An IPR Petition Is Subject To A One-Year Time Bar
Anyone who is not the owner of a patent may file an IPR petition with the Board. In general, an IPR petition may be filed any time after nine months of the issuance of the challenged patent. However, once being served with a complaint alleging patent infringement, a party has one year to file an IPR petition. If a party has been served with more than one complaint asserting the same patent, the serving date of the earliest complaint applies. 
The one-year bar is strictly applied; in fact, the only way to get around this one-year bar is by requesting a joinder under 35 U.S.C. § 315 (c), which authorizes the Board to join a party to an instituted petition challenging the same patent. Although a joinder can be requested after the one-year time period, it must be filed within one month after the institution date of the petition for which the joinder is requested. In the above hypothetical, if Y has been served with the complaint more than one year ago, Y, within one month of the institution date of X’s petition, can still file its IPR petition by concurrently filing a motion for joinder.
Joinder To Another Party’s Petition Is Subject to the Board’s Discretion And May Be Denied
Once a motion for joinder is filed, it may or may not be granted. In fact, joinder is far from automatic and is at the discretion of the Board. In determining whether to grant a motion for joinder, “the Board considers the impact of both substantive issues and procedural matters on the proceedings, as well as other considerations.”
Although the Board has granted more than two thirds of joinder requests, the Board is more likely to deny a joinder request if it has the effect of extending the proceedings already progressing, for example, if the joinder request raises new grounds, prior art references, or arguments, introduces new evidence, or requires additional discovery that have not been present in the previously instituted IPR. One panel even expressly stated that “where two parties file nearly identical petitions in separate proceedings, joinder is not granted as a matter of right.” That panel denied the joinder because the later-filed petition required additional discovery and would delay the instituted proceeding and four related proceedings.
Further, the Board is more likely to deny joinder if it would have a substantial impact on the trial schedule of the instituted proceeding, such as a delay of six months or longer. Another procedural consideration is whether the petitioner seeking joinder has addressed how briefing and discovery may be simplified. The Board also considers whether joinder would prejudice any parties, whether there is any pending related proceeding, and whether the schedule could be modified to allow for a final written decision within one year of institution.
A Party May Join Its Own Instituted Petition If Additional Claims Are Asserted
Although joinder is often allowed when one alleged infringer requests to join a petition filed by another alleged infringer, what about when a party filed an IPR which has already been instituted, and later seeks to join its own instituted petition? This most often arises when the patent owner asserts additional claims after an IPR has already been instituted, such as with respect to party X in the above hypothetical. Often the one-year period in which to file an IPR has passed. If X wants to challenge the newly asserted claims, it must seek a joinder to obviate the time bar.
Filing a joinder to a party’s own petition can be risky and it may be denied. One panel interpreted Section 315(c) as joinder of a party, not proceedings, and therefore “once a petitioner is time barred under Section 315(b), it is always time barred.” That panel denied joinder as untimely. Earlier decisions by other panels, however, have allowed such joinder requests because the statute does not prohibit the joinder of proceedings by the same party. It is unclear whether the split between panels would be resolved any time soon. Thus, a defendant seeking this kind of joinder must be mindful about the possible opposite outcomes.
A defendant, at the onset of a patent litigation, should carefully evaluate its defense strategies and be wary of the subtleties relating to the IPR one-year bar. It is generally advisable that a litigant consider filing a petition within the one-year limit to ensure that its petition can be instituted, even without a joinder. If a litigant needs to join an already instituted IPR petition filed by another party in order to avoid the one-year bar, the litigant runs the risk that the joinderrequest may not be granted. This means that Y in the above hypothetical would have to rely on X to obtain a favorable final written decision from the Board with respect to the patent. Not only does Y forfeit the possibility of providing any input, Y also runs the risk of exposure because X could settle out or be unsuccessful in invalidating the patent. Additionally, when negotiating case management schedules and determining the latest date by which a plaintiff can add more patent claims, a patent infringement defendant should carefully consider how this will affect its strategy with respect to the timing of any IPR filing. It is a possibility that the Board may deny the joinder of additional claims to an IPR already instituted by the defendant itself.
 35 U.S.C. § 311 (a).
 Id. § 311 (c).
 Id. § 315 (b).
 Apple v. Virnetx, Inc. et al., Paper 14 at 4.
 Id. § 315 (b).
 37 C.F. R. § 42.122(b).
 Id. The Board has denied joinder filed more than one month after the institution date of the petition for which the joinder was requested as untimely. See, e.g., Google Inc. v. PersonalWeb Technologies, LLC, IPR2014-00977, Paper 10.
 See 35 U.S.C. § 315 (c); see also Sony Corp. et al v. Network-1 Security Solutions, Inc., IPR2013-00386, Paper 16 at 6; see 37 C.F.R. § 42.1(b) (“The fact that the Board has the discretion to join a party does not mean that joinder is automatic, particularly given the need to complete proceedings in a just, speedy, and inexpensive manner.”).
 Motorola Mobility LLC v. Softview LLC, IPR2013-00257, Paper 10 at 4.
 See, e.g., NetApp, Inc. v. PersonalWeb Technologies, LLC, IPR2013-00319, Paper 18 at 5 (denying joinder because the petition challenged a new claim, and added new declarations and arguments); Sony Corp., IR2013-00386, Paper 16 at 7 (denying joinder because the petition challenged a new claim, asserted new grounds of unpatentability, and asserted new prior art references); Unified Patents, Inc. v. PersonalWeb Technologies, LLC, IPR2014-00702, Paper 12 at 5 (denying joinder because the patent owner may need additional discovery to determine who was the real-parties-in-interest).
 Unified Patents, Inc., IPR2014-00702, Paper 12 at 5.
 Id. at 5-7.
 See Sony, IPR2013-00386, Paper 16 at 8 (noting that joinder would have a substantial impact on the trial scheduling for the existing proceeding because joinder would “require delaying the upcoming due dates… and extending the overall schedule by many months”); SDI Technologies, Inc. v. Bose Corp., IPR2014-00346, Paper 15 at 4 (denying joinder because the trial schedules in the two proceedings “are out of synchronization by roughly six months”).
 Sony, IPR2013-00386, Paper 16 at 9 (denying joinder because petitioner failed to “explain in detail what procedures should be followed or how such procedures would minimize the impact on the current schedule”); Samsung, IPR2014-01142, Paper 11 at 5 (denying joinder because the petitioner did not suggest any specific changes to the schedule in the instituted petition other than suggesting that it would have seven additional pages for papers filed).
 See Ariosa Diagnostics v. Isis Innovation Ltd., IPR2013-00250, Paper 24, at 5; Motorola, IPR2013-00257, Paper 10 at 10; Unified Patents, 2014-00702, Paper 11 at 5.
 Target Corp. v. Destination maternity Corp., IPR2014-00508/00509, Paper 18.
 See e.g. Ariosa Diagnostics v. Isis Innovation Ltd., IPR2012-00022, Paper 66; Microsoft, IPR2013-00109, Paper 15; ABB Inc. v. Roy-G-Biv Corp., IPR2013-00282, Paper 15.