Majority voting not in Constitution

Does the U.S. Constitution prescribe majority votes in Congress?

This question came up in the Volokh Conspiracy forum.

The answer is no. Here is my comment:


The Constitution nowhere provides that a simple majority, either of the body or those present, is sufficient to pass a bill. What it does provide:

1. That the House have “Power of Impeachment”, but nothing on a voting rule.
2. That that state legislatures “chuse” U.S. senators. No mention of by what vote.
3. That the Vice President shall have a vote if the Senate is “equally divided”, but not when if ever they might be equally divided.
4. That each house shall “chuse” their officers, but no mention of by what vote.
5. Senate requires 2/3 of members present to remove on an impeachment.
6. Majority of members of each House to be a quorum, but nothing about voting rules for business, except as provided for specific kinds of issue.
7. Submajority may adjourn or compel attendance.
8. Each House may determine its own rules of procedure, but does not specify by what vote rules are to be adopted, amended, etc.
9. 2/3 of members of a House required to expel a member.
10. 1/5 of members present may require a record vote in either House.
11. 2/3 of members of each House required to pass bill over a veto.
12. 2/3 of Senate members present required to consent to treaties.
13. 2/3 of members of each House required to propose amendments.
14. 2/3 of state legislatures required to propose amendments or call constitutional convention.
15. 3/4 of state legislatures or conventions required to adopt amendments.

Congress and state legislatures used variants on the rules of procedure of the British House of Commons, which contained supermajority rules on some points. The rules were codified in Jefferson’s Manual of Parliamentary Procedure, which evolved into Robert’s Rules of Order, as adapted to Congress.