The U.S. Constitution requires that any proposed law that is given to the President for signature, must pass both the House and Senate in the exact same form. When the House passes one version of a bill, and the Senate passes another, one way of resolving differences is for one body to pass an amendment to a bill, and then seek agreement by the other chamber. For example, The Senate amends a House bill, and then the bill is sent back to the House. If the amendment is accepted, the measure is sent to the President.
If the amendment is rejected, the House may ask the Senate for a Committee of Conference which consists of House and Senate Members appointed by the presiding officer of each body. These members are charged with the obligation of figuring out how to reach agreement, if that is possible. If there is a matter upon which the House does not want to change its view, a motion bay be offered to instruct the House Conferees to follow that instruction. This motion is usually not amendable. The “instructions” are not binding, but they offer the House a way to gage the support and opposition to a legislative matter.
Voting in the Committee of Conference is taken separately by each body where a majority of conferees must agree to amendments. So, if there are five Senate Conferees, and five House Conferees, five Senate members and one House member would not make a majority of the Conference. For there to be agreement in that case, at least three House members, and at least three Senate members would have to agree on amendments or motions. Thus, the same numbers of conferees in favor and in opposition to an amendment (six “yes,” four “no”)would produce entirely different results.
But once agreement has been reached, the measure is reported back to the House and Senate. It is important to remember that a conference report may not be amended on the House floor. When conferees cannot reach agreement on all the items they were supposed to deal with, the House and Senate conferees will separately present a conference report to their respective bodies which will include all amendments upon which agreement was reached but will exclude the matters or amendments that remain in real or technical disagreement. The conference report, with amendments agreed upon by both sets of conferees, is voted on first, and then the left-over amendments in disagreement are voted on separately.