35 USC 314(d) seems clear on its face:

(d) NO APPEAL. — The determination by the Director whether to institute a review under this section shall be final and nonappealable.

The Board’s decision whether to institute inter partes review is not reviewable.  However the statute is not enough to keep parties from trying.  In St. Jude Medical, Cardiology Division, Inc. v. Volcano Corp., 749 Fed 1373, 1375-76 (Fed. Cir. 2014), St. Jude tried to appeal the Board’s decision denying St. Jude’s petition for inter partes review, but the Federal Circuit dismissed the appeal based on the broad bar of 35 USC 314(d).  The Federal Circuit has also held that a decision not to institute is cannot be challenged with a Writ of Mandamus, because  in view of 35 USC 314(d), a disappointed petitioner has no “clear and indisputable” right to relief.  In re Dominion Dealer Solutions, 749 F.3d 1379, 1381 (Fed. Cir. 2014).

The Patent Owner is in no better position, the Federal Circuit denying Writs of Mandamus to patent owners attempting to challenge the Board’s decision to institute inter partes review.  In re Proctor & Gamble, 749 F.3d 1376. 1378-79 (Fed. Cir. 2014); see, also, In re Board of Trustees of the University of Illinois, 564 Fed. Appx. 1021 (Fed. Cir. 2014); In re Versata Development Group, Inc., 564 Fed. Appx. 1024 (Fed. Cir. 2014).  However, the Federal Circuit has expressly left open the possibility that an institution decision might be reviewable incident to the appeal of an final written decision.  In re Proctor & Gamble, 749 F.3d 1376. 1378-79 (Fed. Cir. 2014).

The review of the institution decision incident to the appeal of a Final Written Decision  is before the Federal Circuit in In re Cuozzo Speed Technologies LLC, [14-1301] (Fed. Cir.).  Cuozzo has argued that there are some decisions that should be reviewable, for example if the Board were to institute inter partes review based on §101 grounds (which is not provided for by statute).  Even the Patent Office, which intervened in the appeal, appeared to conceded that the restriction on appeal may be limited to the merits of the decision on patentability.

The Federal Circuit may provide some after-the-fact review for patent owners, but is there really no review of the decision of the Board no matter how contrary to the regulations and statutes?  Practitioners might consider a Petition to the Commissioner under 37 CFR §1.182:

All situations not specifically provided for in the regulations of this part will be decided in accordance with the merits of each situation by or under the authority of the Director, subject to such other requirements as may be imposed, and such decision will be communicated to the interested parties in writing. Any petition seeking a decision under this section must be accompanied by the petition fee set forth in §1.17(f).

The Commissioner should have the inherent authority to correct a serious error by the Board, although the Commission will likely not get involved in the merits of the preliminary patentability determination.

, because the decision not to institute was not a Final Written Decision,314(d) . olcano that is not enough to keep parties from trying.