The rule that all bills die when a Congress ends is an unwritten rule, based on precedent. It is part of a more general rule: All unfinished business dies when a Congress ends. The logic of this rule is simple: Because every member of the House is elected every term, every new Congress is considered a separate Congress. To require a new Congress to take up the unfinished business of the previous Congress would violate yet another, more general rule: “No Congress can bind its successors.” This rule came from England, where it was thought to be a direct implication of parliamentary supremacy. In the US, it is justified either as implied by the constitution, or by practical political realities.
What the Congressional manuals say
The rule “all business dies” is mentioned in several of the standard compilations of Congressional practice and precedent. These compilations, (available online from the GPO,) include House Practice:
However, because past proceedings of one Congress do not bind its successor, business remaining at the end of one Congress does not carry over to the beginning of a new Congress (with the exception of impeachment).
Precedents of the House, § 8. Legislative Business of a Prior Session:
Each Congress is a separate parliamentary body that comes into being at assembly and terminates upon sine die adjournment. Thus, it is generally the case that business of one Congress does not continue as business of the next Congress. For example, bills and resolutions introduced in one Congress cannot be taken up in a subsequent Congress but must be formally reintroduced. Unfinished business pending at the close of one Congress does not remain unfinished business of a subsequent Congress.
Decschler’s Precdents, Ch. 1 § 11,
The vast majority of business remaining at the end of one Congress does not, however, carry over to the beginning of a new Congress, since Congress does not allow the past proceedings of one Congress to bind its successor. Few categories have carried over from one Congress to the next; impeachment proceedings pending on the last day of one Congress have been continued at the beginning of the succeeding one, and a Presidential veto message to the House was on one occasion read and received at the beginning of the next Congress.
Legislative Entrenchment: Why Congress Can't Bind
The idea that one legislature cannot bind a later legislature is known as the rule against ”legislative entrenchment.” This rule traces back to England, where it was first stated by Edward Coke, in his Institutes of the Laws of England, published in 1644.
Acts against the power of the Parliament subsequent bind not.
In England, the rule was seen as a direct implication of parliamentary sovereignty. Thus, in his Commentaries on the Laws of England, William Blackstone argued that to allow one parliament to bind another would be logically inconsistent with the idea of parliamentary supremacy:
Because the legislature, being in truth the sovereign power, is always of equal…absolute authority: it acknowledges no superior upon earth, which the prior legislature must have been, if its ordinances could bind a subsequent parliament.
Interestingly, during the Revolution, an American colonist, writing as Cassandra, used the rule against entrenchment to argue for independence. He quoted Coke to claim that because no Parliament could bind future Parliaments, any British promise to respect the rights of colonists was not, as the game theorists would say, credible.
It is out of the power of the British Legislature to give us security for the future enjoyment of our rights and liberties…Is there safety in entering upon terms of accommodation with a power which cannot stipulate for the performance of its engagements?
In reaction to such criticisms of the British system of Parliamentary supremacy, Americans decided to adopt a written constitution. The Americans argued that while a legislature might not be able to bind itself, the people, acting through the Constitution, could bind the legislature.
Instead of invoking Parliamentary supremacy, Americans justified the “no Congress can bind” rule by appealing to the Constitution (ie, the electoral cycle + the vesting clause = every Congress is a new Congress, which alone is vested with the legislative power under Art. I, § 1), or to practical considerations (it is impossible for today’s Congress to enforce a binding clause on a later Congress, which could simply pass a new statute). (For fuller discussion of these arguments, see here.)
Unwritten Rules in the House
Here is what House Practice, Ch. 50. Rules and Precedents of the House, says about Rules Based on Precedent or Custom:
Much of what is known as parliamentary law is not part of the formal written rules of the House but springs from precedent or long-standing custom. Such precedent may be invoked to resolve a procedural question in the absence of an express written rule on the subject. More frequently, the precedents of the House are used to show the scope and application of one of its formal rules…
On the theory that a government of laws is preferable to a government of men, the House has repeatedly recognized the importance of following its precedents and obeying its well-established procedural rules. The House adheres to settled rulings, and will not lightly disturb procedures that have been established by prior decision of the Chair. However, the Speaker or Chairman may refuse to follow a precedent even though it is relevant to a pending question, where it is the only precedent on the point and was not carefully reasoned.