On Monday, Clarence Thomas admitted that he had routinely failed to disclose information about his wife’s employment, as he is required to do by federal law, but said the failure was inadvertent.

Thomas, who as you may recall is an Associate Justice of the U.S. Supreme Court, said he didn’t understand the filing instructions for the form.

Thomas was reacting to criticism from (among others) the group Common Cause, which noticed the omission from forms required by the Ethics in Government Act. On Monday, he sent eight letters to the judicial branch’s Committee on Financial Disclosure, each referring to a particular year or years and each stating only: “It has come to my attention that information regarding my spouse’s employment . . . was inadvertently omitted due to a misunderstanding of the filing instructions. Please amend my report [accordingly.]” (Note the use of the passive voice: “Information . . . was inadvertently omitted” by whom— the maid?)

The misunderstanding came in part III.B. of the 2009 form, which asks for the sources of “Spouse’s non-investment income.” Thomas checked the box next to the word “NONE.” If there are separate instructions for the form, I haven’t been able to find them online. If not, the instructions really do not seem that complicated.

But maybe the laws underlying the form are complicated, and Justice Thomas was just overthinking things. Let’s see.

• “Persons required to file” the disclosure form . . . nope, it includes “the Associate Justices of the Supreme Court.” 5A U.S.C. §§ 101(f)(11), 109(10). He’s one of those.

• Spouses . . . no, says each report must include “the source of items of earned income earned by a spouse from any person which exceed $1,000 . . . .” 5A U.S.C. § 102(e)(1)(A). Did Mrs. Thomas earn more than $1,000 in any particular year? Yes, almost $700,000 in the last six years. That’s more than $1,000 (and also more than “none”).

• Wait—maybe “income” only means amounts paid in the type of money used at the time the Constitution was adopted!  —No, seems to mean all kinds of income.  5A U.S.C. § 109(7).

Well, it still seems pretty straightforward to me. I’m not saying these laws are in plain English, but you know what? If you are going to be on the Supreme Court, you really can’t claim to have trouble with the meaning of “none.”

By the way, this is a nonpartisan criticism, as I will demonstrate by noting that I said the same kind of thing about Tim Geithner after he claimed he was confused by tax laws at a time when he was hoping to be confirmed as Secretary of the Treasury. See “Tax Returns Are Hard, Says Federal Reserve Bank President,” Lowering the Bar (Jan. 21, 2009).

In a statement, a representative of Common Cause said he found Thomas’s explanation “implausible.”