This seems to be the most relevant portion of the decision (viewable in full here: http://www.scribd.com/doc/33661051/Supreme-Court-Ruling-on-S...). From pages 28-29, with citations removed for readability:
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"We reject such a broad holding. Instead, we agree with the Government that the unconstitutional tenure provisions are severable from the remain der of the statute. “Generally speaking, when confronting a constitutional flaw in a statute, we try to limit the solution to the problem,” severing any “problematic portions while leaving the remainder intact.”
"Because “[t]he unconstitutionality of a part of an Act does not necessarily defeat or affect the validity of its remaining provisions,” ... the “normal rule” is “that partial, rather than facial, invalidation is the required course”.
Under the traditional default rule, removal is incident to the power of appointment. Concluding that the removal restrictions are invalid leaves the Board removable by the Commission at will, and leaves the President separated from Board members by only a single level of good-cause tenure. The Commission is then fully responsible for the Board’s actions, which are no less subject than the Commission’s own functions to Presidential oversight.
The Sarbanes-Oxley Act remains “‘fully operative as a law’” with these tenure restrictions excised. We therefore must sustain its remaining provisions “[u]nless it is evident that the Legislature would not have enacted those provisions independently of that which is [invalid].” Ibid.
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