concurring in part and dissenting in part:
While I concur in the court’s decision that the motion to compel arbitration was erroneously denied by the district court, I respectfully disagree with its conclusion that the waiver issue was for the court to decide. In my view, arbitrability is a matter for the court; whether or not the agreement to arbitrate was properly invoked, by either side, at any time, is a matter for the arbitrator to decide. Thus I would reverse on the very narrow ground that a motion to compel must be granted because the arbitration clause is valid. I would leave all other issues to the arbitrator.
I
As the en banc opinion in Nagrampa v. Mailcoups, Inc., 469 F.3d 1257 (9th Cir.2006) (en banc) has revealed, there are continued tensions in our arbitration jurisprudence which have failed to clarify this area. Very recently, the Supreme Court has renewed its commitment to support arbitration in Hall Street Associates, L.L.C. v. Mattel, — U.S.-, 128 S.Ct. 1396, 1402, 170 L.Ed.2d 254 (2008). But Prima Paint Corp. v. Flood & Conklin Manufacturing Co., 388 U.S. 395, 400, 87 S.Ct. 1801, 18 L.Ed.2d 1270 (1967) (holding that a federal court must “order arbitration once it is satisfied that an agreement for arbitration has been made and has not been honored”), Howsam v. Dean Witter Reynolds, Inc., 537 U.S. 79, 85, 123 S.Ct. 588, 154 L.Ed.2d 491 (2002) (holding that “in the absence of an agreement to the contrary, issues of substantive arbitrability ... are for a court to decide and issues of procedural arbitrability, ie., whether prerequisites such as time limits, notice, *1127laches, estoppel, and other conditions precedent to an obligation to arbitrate have been met, are for the arbitrators to decide ” (quoting the Revised Uniform Arbitration Act of 2000 (RUAA) § 6(c) cmt. 2) (emphasis added and in the original)), Buckeye Check Cashing, Inc. v. Cardegna, 546 U.S. 440, 449, 126 S.Ct. 1204, 163 L.Ed.2d 1038 (2006) (“[A] challenge to the validity of the contract as a whole, and not specifically to the arbitration clause, must go to the arbitrator.” (emphasis added)), and Nagrampa, 469 F.3d at 1293-94 (holding that an arbitration agreement that was invalid due to unconscionability was not enforceable), are absolutely clear that once the legal decision is made by the court that an arbitration clause is valid, all remaining issues are for the arbitrator.
The Supreme Court in Howsam could not be clearer: “the presumption is that the arbitrator should decide allegations] of waiver, delay, or a like defense to arbi-trability.” 537 U.S. at 84, 123 S.Ct. 588 (internal quotation marks and citation omitted). Thus, I find perplexing the majority’s attempt to distinguish Howsam.
Here, I see no relevant distinction between Cox’s attempt to avoid the arbitra-bility of his employment dispute based on whether or not he properly followed the procedures of the AAA and Dean Witter’s challenge to arbitrability in Howsam based on the National Association of Securities Dealers (NASD) procedural rules. See Howsam, 537 U.S. at 81, 123 S.Ct. 588. In this case I would follow the reasoning of the Supreme Court in Howsam that “[because the parties would likely have committed interpretation of a[AAA] rule to a[AAA] arbitrator, that particular issue of procedure was left for the arbitrator to decide.”1 Opinion at 1121 (citing Howsam, 537 U.S. at 86,123 S.Ct. 588).
Here, neither party disputes the existence nor validity of the arbitration agreement. Therefore, I concur in the majority’s decision to compel arbitration. However, I would remand all other issues to the arbitrator, including the issues of whether the arbitration provision was waived or breached, and therefore dissent to the extent the court holds otherwise.2 *1128See Howsam, 537 U.S. at 85, 123 S.Ct. 588.
II
Let me add that I find the majority’s treatment of Brown v. Dillard’s, Inc., 430 F.3d 1004 (9th Cir.2005), to be problematic and I would not reach it. If I, rather than the arbitrator, were to reach the question of whether or not arbitration was properly invoked, however, I would reluctantly conclude that Bromi controls this case. In my view, there is simply no principled difference between the holding that Ms. Brown properly invoked arbitration in Brown and the district court’s finding that Mr. Cox properly invoked arbitration here.
. Such approach is correct notwithstanding the majority's citation to out of circuit cases considering waiver based on extensive participation in litigation. See, e.g., Khan v. Parsons Global Servs., 521 F.3d 421, 428 (D.C.Cir.2008) (holding that Parsons waived right to compel arbitration by “filing a motion for summary judgment based on matters outside of the pleadings”); In re Tyco Int’l Ltd. Sec. Litig., 422 F.3d 41, 43, 46 (1st Cir.2005) (considering question of waiver after the "AAA dismissed the Tyco demand for arbitration ... for lack of written consent”); PPG Indus., Inc. v. Webster Auto Parts Inc., 128 F.3d 103, 107 (2d Cir.1997) (holding that “a party waives its right to arbitration when it engages in protracted litigation that prejudices the opposing party” (emphasis added)); Great W. Mortgage Corp. v. Peacock, 110 F.3d 222, 233 (3d Cir.1997) (“Indeed, a party waives the right to compel arbitration only in the following circumstances: when the parties have engaged in a lengthy course of litigation, when extensive discovery has occurred, and when prejudice to the party resisting arbitration can be shown.” (emphasis added)).
. The majority opinion states that my approach leads to "a strange result: the arbitrator would get first crack at defenses to a motion to compel arbitration based on waiver or breach.” Opinion at 1121 n. 5. However, the majority opinion's approach is no less strange; it would require a court to answer the question of waiver before deciding whether the question of waiver is one for the arbitrator to decide. See Opinion at 1120 n. 4, 1120-21. Such an approach leads to a waste of judicial resources should the court find that the arbitration clause was not breached or waived and it does take into account the FAA's policy favoring enforcement of arbitration agreements. Although not directly on point, Buckeye Check Cashing instructs us that when faced such a “conundrum” we must "resolve[j it in favor of the separate enforceability of arbitration provisions.” 546 U.S. at 448-49, 126 S.Ct. 1204.