The motion to instruct conferees is offered at the time the House or Senate vote to go to conference with the other body to resolve differences between their respective versions of a bill. If adopted, this motion instructs Members representing the chamber in conference to take a specific position in the negotiations.

You are right that, even if adopted, instructions are not binding upon the conferees. They are only advisory in nature. There is no enforcement of the instructions available in either chamber beyond rejecting a conference report which failed to meet the instructions.

The idea behind conference negotiations is to resolve difference through free discussions. Binding conferees would diminish the flexibility required to strike successful compromises. As a result, even if instructed, conferees are free to use the instructions or to ignore them. If used, they can be treated as leverage in negotiations with the conferees from the other chamber. The opinions expressed in the instructions become the basis for the House or Senate conferees to argue to their counterparts why they dare not concede specific provisions in dispute. Alternatively, the instructed conferees can choose to ignore the instructions completely if they present an impediment in the negotiations.

Instructions may ask conferees only to uphold very general policy goals; or they may specifically advise the conferees to defend a specific provision in their chamber's bill; or they may instruct the conferees to reject specific provisions in the other chamber's bill.

One of several motives may be behind the offering of a motion to instruct conferees:

• to send the other chamber a clear message on the policy parameters the House or Senate as a whole will accept
• to exert political pressure upon the conferees to conform to their chamber's will
• to give conferees support in tough negotiations
• to get debate time on the floor to discuss the issue contained in the instructions
• to create a vote on the issue for the political record. Even though instructions are only advisory and not the same as statutory language, this distinction is often lost on the campaign trail.

There are differences between how the House and Senate treat motions to instruct conferees. Many more are offered in the House than in the Senate. In the House, the motion is reserved for minority party Members – one of only two motions in the House prioritized for the minority [the other being the motion to recommit]. Since it is difficult for minority Members in the House to get floor time for their issues in a chamber where the majority is given total control over the agenda, motions to instruct provide them with a rare opportunity to debate topics of their choice.

In the Senate there is no party restriction: any Senator may offer the motion. Senators offer far fewer motions to instruct than do House Members. That may be because they are too busy "instructing" conferees informally in the hallways since personal negotiations are so much part of the Senate culture, or it might also be because Senators have so many opportunities to bring their own substantive and political points to the floor in the normal amending process, that they do not need to use this device for agenda-raising.

Another difference is in timing. Only one motion to instruct conferees is in order at the time the House votes to go to conference on a bill. However, if conferees have met without resolution for 20 calendar days after they were appointed, additional motions to instruct are allowed. At this later stage, there is no limitation on the number of motions to instruct that may be offered. Nor is the motion reserved for the minority party at this stage. Any Member may offer it. However, the Member must notify the House of his intent to offer the motion in advance and wait for the Speaker to provide him a time slot to do so on the next day the House meets. The rationale behind the 20-day rule is that conferees who have been unable to produce a conference report after that length of time may need the advise and guidance of their parent chamber.

In the Senate, after the initial motion has been offered, the conferees still can be instructed at any time while a bill is in conference, and by any Senator. It is done through submitting a resolution, requiring a majority vote of the Senate to take effect.