As a recent example, the recent $2.3 trillion stimulus bill contained not just provisions related to supporting the American people, but also a requirement to produce a report on UFOs:

Federal agencies have been asked to publish a report on unidentified flying objects (UFOs) in less than 180 days, thanks to an act included in the $2.3 trillion stimulus and government spending bill signed by President Donald Trump on Sunday.

A report by the Select Committee on Intelligence attached to the The Intelligence Authorization Act for 2021 states that the Director of National Intelligence, the Secretary of Defense and the heads of other relevant agencies submit a report to the congressional intelligence and armed services committees on "unidentified aerial phenomena (also known as "anomalous aerial vehicles''), including observed airborne objects that have not been identified." They are asked to do this 180 days after the act is enacted.

Are there countries where a proposed law may only focus on one single topic?

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    Whomever gets to decide what is "on topic" would have great power to shape and block legislature. Best to not vest that in one person, or party, or committee. Perhaps the whole chamber should vote on it. :)
    – Schwern
    Commented Jan 2, 2021 at 21:17
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    However, what you describe here is generally valid and known as "lighting up the Christmas tree" en.wikipedia.org/wiki/Christmas_tree_bill Commented Jan 2, 2021 at 22:11
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    This was not a $2.3 trillion stimulus bill. It was instead a $1.4 trillion omnibus spending bill that the Congress had worked on for many months, plus a $900 billion stimulus addendum added at the last moment. The omnibus spending bill in turn comprises twelve separate bills that Congress decided to package together as one single bill. Like it or not, some small but arguably objectionable things (and this silly UFO investigation is a small thing) inevitably get inserted into these spending bills. "It is what it is." Commented Jan 2, 2021 at 23:43
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    Coronavirus relief is a big deal so it's understandable that commentary would focus on that but it resulted in a frequent mischaracterization of the bill. This is not a “stimulus bill” but an omnibus spending bill that was required for the government to continue to function and by nature covers many different topics. If you are looking for a bill with a clear focus and a discussion of riders in general, this is one of the worse examples you could find.
    – Relaxed
    Commented Jan 2, 2021 at 23:53
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    @DavidHammen Why is that "inevitable"? That makes it sounds like some sort of force of nature, but what if we lived in a world where politicians behaved like honest professional adults (ha ha)?
    – gerrit
    Commented Jan 4, 2021 at 9:06

7 Answers 7


Depending on how one defines "one single topic", the rule applies in the UK.

Erskine May - the bible of parliamentary procedure in the UK - has this to say on the scope of a bill:

Any amendment (or new clause or new schedule) proposed to a bill must be within its scope. The scope of a bill represents the reasonable limits of its collective purposes, as defined by its existing clauses and schedules. In particular cases, difficult questions of judgment may arise. The scope of a bill, particularly of a bill with several purposes, may be wider than its long title, although the long title may help to determine the scope.

In other words, a bill's long title is intended to summarise the scope of the bill. Any amendment which is outside that scope is likely to be ruled out of order.

Admittedly, that's not quite the same as saying that a bill must only contain matters pertaining to a single subject; but that is the effect, and so omnibus bills are unknown in the UK (at least nowadays).

Note that this does make riders ("an additional provision added to a bill [...], having little connection with the subject matter of the bill.") all but impossible; and amendments relating to money can only be made by the government.

It's less clear what happens if any content in the original bill (before any amendments are made) fails to match the long title. It may be that amendments are made either to remove the offending clauses, or to amend the long title to reflect the actual contents of the bill.

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    +1 but budgets are generally not subject to this. One doesn't pass separate laws to fund the armed forces vs the NHS, as far as I know. In fact looking at an actual UK budged, I'm sure of that assets.publishing.service.gov.uk/government/uploads/system/… Commented Jan 2, 2021 at 21:49
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    @Fizz a complementary piece of parliamentary procedure, which prevents riders being added to budgets, is that unlike in the US, if a budget isn't passed, this is treated as a vote of no confidence, which automatically triggers a general election, where all seats are up for grabs. I feel like if congress knew that it was their jobs that would be lost if they blocked an appropriations bill, government shutdowns and riders on budgets in the US would not be a thing.
    – James_pic
    Commented Jan 4, 2021 at 12:17
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    @James_pic - true, though since the passing of the Fixed Term Parliaments Act, this is no longer automatic. However, that Act is likely to be reviewed this year, so things could conceivably go back to how they were. Commented Jan 4, 2021 at 12:36
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    @SteveMelnikoff I think probably what is more important, is that in Britain, political parties - and especially party whips - have a bigger part to play than is the case in the US. The US riders to bills, are the result of "pork-barrel" politics where individual members (eg someone interested in UFOs) can, when votes are being canvassed, find they are powerful enough to insist upon a rider. Any MP in Britain trying that would first have to answer to his whip. Parties are more powerful in the UK than in the US.But +1 for the answer.
    – WS2
    Commented Jan 4, 2021 at 23:37
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    @PhillS The "long title" of that Act is "An Act to Repeal the European Communities Act 1972 and make other provision in connection with the withdrawal of the United Kingdom from the EU." The short title doesn't strictly need to be descriptive, only distinctive, as it's used to cite the Act in other legal documents. On the other hand, short titles tend towards boringly to-the-point rather than the catchy titles and acronyms more favoured in the US, so "Great Repeal Act" was a rather pompous suggestion even if it had described the contents.
    – IMSoP
    Commented Jan 5, 2021 at 11:45

Riders are forbidden in France, where the constitutional court (conseil constitutionnel) simply nullifies them whenever it reviews a bill. Rules are stricter now than they used to be and the court is enforcing them more aggressively in the hope of making them worthless. Obviously, any process or measure that prevents unrelated amendments to a bill restricts the freedom and independence of the parliament and this one is no exception.

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    " is enforcing them more actively in the hope of making them worthless" => can you expand on that? Google Translate doesn't give a very good picture. Commented Jan 3, 2021 at 0:18
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    @JonathanReez: basically the article says that the CC (which actually made up this rule circa 1985) is enforcing it even more strictly since 2006. However looking a graph further in the article, it doesn't look like that's really working... Commented Jan 3, 2021 at 1:20
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    @JonathanReez; Then, apparently the French constitution was amended (article 45) in 2008 with respect to riders. It's not clear if that has made any difference... but the new article allows an "indirect link". Commented Jan 3, 2021 at 1:27
  • @Fizz If you follow the reasoning of the author, it seems to have an effect. The first chart plots reportedly suggests the CC was less strict around 2013-2015, which was followed by a new peak in unrelated riders in 2014-2017 (second chart). Being more aggressive then brought them back down.
    – Relaxed
    Commented Jan 3, 2021 at 9:33

Theoretically, there is a rule regarding this in the Romanian legislation. Article 14 of the Law 24 from 2000 says "an act may include normative regulations regarding other related matter only insofar as they are essential for attaining the desired purpose of this act". However, in practice this rule is often ignored (sometimes, Emergency Government Ordinances contain changes to various unrelated laws).


Greece's constitutional provisions regarding parliamentary procedure forbid the parliamentary discussion of bills containing unrelated topics. Specifically, article 74, paragraph 5 of the Greek Constitution (also available in English) stipulates that a) a law proposal containing provisions not related to its main subject matter shall not be introduced for debate, and b) no addition or amendment shall be introduced for debate if it is not related to the main subject matter of the Bill or law proposal.

In practice these rules are honored in the breach rather than the observance. The Constitution also stipulates that Parliament rules on any disputes related to these rules, and, I guess, this is the loophole used for discussing and passing bills that do not respect them.


The Czech constitutional court has ruled "wild" riders (addendums completely unrelated to orignal purpose of the law) unconstitutional and has nullified some particular cases (court decision in Czech). The reasoning was that riders make the law unpredictable and hard to understand and make it possible that the rules were not discussed thoroughly and in their full context before they are approved in the leigslative body - all of which contradicts the spirit (although AFAIK not letter) of the constitution. So there is AFAIK no explicit law to forbid riders, but you can litigate to get riders nullified and there is precedent for this to happen.


What Accumulation says is not exactly correct (but too long to put this as a mere comment). Many US state laws nominally forbid riders in legislation passed by their regular legislature:

In 1818, a single subject requirement for bills pertaining to government salaries materialized in the Illinois Constitution. [...] By 1959, some version of the rule had been adopted in forty-three states. The provision in the Nebraska Constitution is typical: “No bill shall contain more than one subject, and the subject shall be clearly expressed in the title.”

As this quotation suggests, single subject rules almost universally include a title provision. This [latter] requirement has independent historical roots, making its inaugural appearance in the Georgia Constitution after the 1795 “Yazoo Land Fraud.” Members of the Georgia legislature passed a bill—titled “An Act for the Payment of the late State Troops”—that transferred vast tracts of public land to private companies. Many politicians profited from the act, which was “smuggled through the legislature under an innocent and deceptive title.” Thereafter, General James Jackson demanded that each bill contain a title that adequately expressed its contents, and a provision to that effect was added to the Constitution in 1798. Many other states adopted similar provisions.

And as a historical precedent perhaps:

the Romans in 98 B.C. forbade laws consisting of unrelated provisions.

The paper also discusses the level of enforcement, but that's probably too long to get to here, but I'll throw in this graph, cumulative over all US states:

enter image description here

The graph is based on a somewhat crude methodology of counting all invocations of the rule(s) in lawsuits, not even necessarily those where the (state) courts even took them into account in their judgement. And also as a map...

enter image description here


Many states in the U.S. have a single subject rule, however those apply to voter-initiated legislation, not to legislation introduced by the legislature.


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