The BYRD RULE is used on the Senate floor to challenge certain language added to a reconciliation bill.

The purpose of reconciliation bills is to reconcile spending levels with revenue levels.

If proposed language steps outside of this primary purpose, it can be challenged on a point of order.

The Byrd rule can be set aside by a 3/5 vote. It is named after its author, Sen. Robert Byrd (D-WV).