Amendment tree diagram. Click on picture for larger image

The "amendment tree" is the colloquial term used to describe the diagram which governs the amending process in the Senate. The diagram shows the possibilities available for offering amendments: the bill under debate is considered the trunk of the tree, and the branches growing out from the trunk illustrate where and in what order amendments can be offered. The House uses the same concept but only has one tree, whereas the Senate has four to choose from, depending on the parliamentary circumstances.

Senator Lott is the Majority Leader of the Senate. In that capacity, he gets favored for recognition over any other Senator. Although it is a very controversial move, Majority Leaders have from time to time used that preferential recognition to offer one amendment after another until all the branches of the amendment tree are full. Until an amendment is voted upon, emptying the branch, no more amendments are in order. This has the effect of shutting out Senators from offering policy alternatives until those favored by the Majority Leader are completed. Majority Leaders have the full procedural right to take advantage of their preferential recognition; however it is not without political cost. Obviously, shutting out other Senators' opportunities to restrict or expand upon the bill text through amendments of their own is controversial. It has often produced resentment -- but also policy victories -- which is why the tactic is still sometimes employed.

The most basic of the four Senate amendment trees permits 3 amendments to be pending simultaneously. The second and third trees permit 5 amendments to be offered. The fourth tree provides for 11, and sometimes 12, amendments to be under consideration at once! Fortunately this latter tree rarely develops. Most of the time, the Senate is content to deal with only 2 or 3 amendments at the same time.

During the amending process, you will certain terms used regularly, e.g. "substitute amendments," "perfecting amendments," "first-degree amendment," among others. Here are some brief definitions: