Senate precedents set out three principles of precedence among amendments that are directed to the same text:
1. A second-degree amendment has precedence over a first-degree amendment;
2. A motion to insert and a motion to strike out and insert have precedence over a motion to strike out; and
3. A perfecting amendment (and an amendment to it) has precedence over a substitute amendment (and an amendment to it).
The first of these principles is axiomatic. A second-degree amendment is an amendment to a firstdegree amendment, and it must be offered while the first-degree amendment is pending—that is, after the first-degree amendment has been offered but before the Senate has disposed of it. The Senate also acts on an amendment to a first-degree amendment before it acts on the first-degree amendment itself. So this principle conforms to Senate practice under both meanings of precedence.
It may be helpful in understanding the second two principles to think about decisions the Senate needs to make about a text. Changing the text of an amendment, through a second-degree amendment, could “cure” a problem Senators may have had with the amendment’s original language. That could obviate the need to strike out the text entirely.-------------------------------------
Creating an exception to the filibuster requires a filibuster-proof majority: TPA
The basic amendment tree in the House: