[Amendment10]

Noting that the Founding States expressly constitutionally allowed non-equal Senate suffrage for specific issues like working with the House to override a presidential veto (1.7.2), I question if the Senate’s practice of supermajority votes for non-enumerated exceptions, such as filibuster, are allowed under the Constitution’s Article V equal suffrage clause for the Senate?

Article V: The Congress, whenever two thirds of both Houses shall deem it necessary, shall propose Amendments to this Constitution, or, on the Application of the Legislatures of two thirds of the several States, shall call a Convention for proposing Amendments, which, in either Case, shall be valid to all Intents and Purposes, as Part of this Constitution, when ratified by the Legislatures of three fourths of the several States, or by Conventions in three fourths thereof, as the one or the other Mode of Ratification may be proposed by the Congress; Provided that no Amendment which may be made prior to the Year One thousand eight hundred and eight shall in any Manner affect the first and fourth Clauses in the Ninth Section of the first Article; and that no State, without its Consent, shall be deprived of its equal Suffrage in the Senate [emphasis added].

Corrections, insights welcome.

[Cboldt]

Suffrage is the right to vote, so the clause you cite is just that each state will have equal power and representation in the senate. That clause doesn't impose a simple majority rule. A simple majority rule isn't expressed because it is (or at least used to be) taken as an obvious feature of a deliberative body.

"Equal suffrage" applies and works properly in the constitutionally prescribed super-majority issues, ratification of treaties, for example. Therefore, equal suffrage isn't a "majority" rule.