There’s a great irony in those who up until yesterday supported the DC Circuit’s strict textualist reading of the ACA now pointing to a statement made by a supporter of the law involved in its drafting as evidence of the statute’s meaning. (Never mind that Gruber now says his statement was a mistake.)
Of course, for textualists, the statements of anyone about the meaning of a statute would seem to be irrelevant (except, according to Justice Scalia, such statements might be admissible to prove that a seemingly absurd reading of a text was actually what was intended).
What about for those who rely on legislative history? For the great majority of judges who do rely on legislative history, committee reports are considered the most reliable. Statements of individual legislators are the least reliable. The statement of Gruber seems less reliable still of evidence of the intent of Congress.
There have been some occasions where judges have relied on statements on nonlegislative drafters, but they are controversial. There is a good discussion in the leading Legislation casebook on this question, Eskridge, Frickey and Garrett, at 1018-20 (notes following Kosak case.) A snippet which comes after explaining why statements of nonlegislative drafters of legislation should not be given much weight:
Notwithstanding these objections, the Supreme Court or individual Justices have occasionally relied on statements by public, nonlegislative officials who draft or promote statutes. [Citations.] Note, however, that (as in Kosak) the Court will not rely on these statements as the most probative — and certainly not the only – evidence of statutory meaning. There are very few state cases; almost all of them either reject or denigrate such evidence. [Citations.]…
At least [the person whose testimony was relied on in Kosak] was a public servant. Should the Court consider authoritative the statements of interest groups which draft and press legislation? In some instances the Court or some Justices have considered testimony about legislation by private groups or individuals who drafted or commented on the legislation.
UPDATE: Ed Whelan responds, going with the anti-absurdity point.