It is natural that

The pattern -는 법이다 is used to state that something is a universal truth, a natural law, or an inevitable outcome. It's like saying "it's the way of things," "it's bound to happen," or "it's a rule that...". It's frequently used in proverbs and when giving life advice.

Formation

This pattern attaches differently depending on the word type.

Action Verbs: Add -는 법이다 to the verb stem.

가다 → 가는 법이다 (is bound to go)

거두다 → 거두는 법이다 (is bound to reap)

Descriptive Verbs (Adjectives): Add -(으)ㄴ 법이다.

Vowel stem: -(ㄴ) 법이다 (e.g., 예쁘다 → 예쁜 법이다)

Consonant stem: -(은) 법이다 (e.g., 좋다 → 좋은 법이다)

Nouns: Add -인 법이다.

약 → 약인 법이다 (is bound to be medicine)

있다 / 없다: Use -는 법이다.

있다 → 있는 법이다 (is bound to exist)

뿌린 대로 거두는 법이야. / 사랑은 변하는 법이야. / 시간이 약인 법이야. / 다 때가 있는 법이야.

-는 법이다 is very similar to another pattern, -기 마련이다. Both express that something is natural or inevitable, and they are often interchangeable.

Key Distinction

-는 법이다: Literally means "it is the law/rule that...". It emphasizes a universal principle, a moral law, or a rule of nature. It often sounds more definitive and is common in established proverbs.

진실은 승리하는 법이다. (It's a rule that truth wins.)

-기 마련이다: Literally means "it is prepared/arranged that...". It focuses more on a natural tendency or an expected outcome in a given situation. It can feel slightly softer, like an observation of what usually happens.

오래 쓰면 고장 나기 마련이다. (If you use it for a long time, it's natural that it breaks down.)

Interchangeability

In many contexts, the nuance is subtle, and you can use either one. Both of the following sentences are perfectly natural.

비밀은 밝혀지는 법이다. (Secrets are bound to be revealed.)

비밀은 밝혀지기 마련이다. (It's natural for secrets to be revealed.)

욕심은 화를 부르는 법이야. / 자식은 부모를 닮는 법이야. / 노력은 배신하지 않는 법이야.

This pattern has distinct casual and polite forms, both of which are very common in daily speech.

Casual Form: -는 법이야

Use -는 법이야 with close friends, family, or people younger than you. It has a confident, sometimes didactic tone, as if you're sharing a piece of wisdom or stating an undeniable fact.

Context: When comforting a friend who made a mistake, you might say, 누구나 실수하는 법이야. (Everyone makes mistakes.)

Polite Form: -는 법이에요

Use -는 법이에요 in most other situations, such as with colleagues, acquaintances, or elders. It softens the statement, making it sound more like a gentle observation or a shared understanding of how the world works.

Context: In a more formal setting, the same idea would be expressed as 누구나 실수하는 법이에요.

거짓말은 들키는 법이야. / 거짓말은 들키는 법이에요. / 만나면 헤어지는 법이야. / 만나면 헤어지는 법이에요.