The U. S. Supreme Court has decided that NASD arbitrators must decide the applicability of the 6 year eligibility rule in the NASD Code of Arbitration Procedure. But who decides the applicability of substantive statutes of limitation in underlying claims, the courts or arbitrators? A New York statute allows a court to determine a substantive statute of limitations, while federal precedents are not in complete accord. Note that recent developments in the law and the adoption in 2007 of the new NASD Customer Code has superseded some of the precedents described in this unpublished article.