Law vs There's only one rule

When to use each in English, with meaning, register, and examples.

Law

Formal Top 1,000 (very common) A2 noun

There's only one rule

Top 2,000 (common)

Most formal: Law Most common: Law

	Law	There's only one rule
Pronunciation	🇬🇧 /["/lɔː/"]/ 🇺🇸 /["/lɔː/"]/	🇬🇧 //ðeəz ˈəʊnli wʌn ruːl// 🇺🇸 //ðɛrz ˈoʊnli wʌn rul//
Meaning	Rules made by a government to keep order.	There is just one guideline or principle.
Example	The law requires that all drivers have insurance.	In this game, there's only one rule: have fun!
Register	Formal	Neutral
How common	Top 1,000 (very common)	Top 2,000 (common)
CEFR level	A2	-
Part of speech	noun
Collocations	administrative, case, civil, become, apply, enforce, allow something, authorize something, permit something, court, case, suit, above the law, against the law, beyond the law, as the law stands, law and order, the law of the land, administrative, case, civil, become, apply, enforce, allow something, authorize something, permit something, court, case, suit, above the law, against the law, beyond the law, as the law stands, law and order, the law of the land, administrative, case, civil, become, apply, enforce, allow something, authorize something, permit something, court, case, suit, above the law, against the law, beyond the law, as the law stands, law and order, the law of the land, practise/​practice, firm, school	follow a rule, break a rule, state a rule
Antonyms	anarchy, chaos	-
Common mistakes	Confused with 'lawsuit' — remember 'law' is a set of rules, while 'lawsuit' refers to a legal case., 'Law' vs. 'rule' — 'law' is official, while a 'rule' can be informal or less strict.	Confusing with phrases like 'there are many rules.', Misusing 'rule' as a verb instead of a noun., Omitting 'only' and changing the meaning.
Usage notes	Use 'law' in formal contexts when discussing legal matters. Avoid in casual conversations unless relevant to the topic.	This phrase is often used in casual conversation to emphasize simplicity. It's appropriate for informal settings, but can also work in neutral contexts.

See it in real clips

- We didn't. - Murphy's Law?

Breaking Bad › S1 E4

We said we'd lay down the law, we lay down the law.

- We didn't. - Murphy's Law?

Breaking Bad › S1 E4

We said we'd lay down the law, we lay down the law.

Law

Right now, there's only one rule:

There's only one rule

Frequently asked questions: Law vs There's only one rule

What's the difference between Law and There's only one rule?

Law: Rules made by a government to keep order. There's only one rule: There is just one guideline or principle.

Which is more formal: Law and There's only one rule?

Law is the most formal of these.

Which is more common: Law and There's only one rule?

Law is the most common in everyday English.

Can you show an example of each?

Law: The law requires that all drivers have insurance. There's only one rule: In this game, there's only one rule: have fun!

Can I use Law and There's only one rule interchangeably?

Not always. Law and There's only one rule are related and overlap in some contexts, but they differ in register, how common they are, and usage, so swapping one for another can change the meaning or tone. Check the differences above before substituting.