The Grammar of Korean Legal Obligations: 해야 한다, 하여야 한다, 할 수 있다, 해서는 안 된다

Core examples: 하여야 한다; 해야 한다; 할 수 있다; 해서는 안 된다; 금지한다; 적용한다; 제1조; 다만; 위반 시.

Everyday grammar becomes legal force

해야 한다, 하여야 한다, 할 수 있다, and 해서는 안 된다 look like ordinary grammar. In legal and regulatory texts, they carry legal force. A learner who translates them casually may miss the difference between duty, permission, discretion, prohibition, application, exception, and consequence.

할 수 있다 in a law does not usually mean “has the physical ability to.” It often grants authority or discretion. 하여야 한다 imposes a duty. 해서는 아니 된다 prohibits action. 다만 introduces an exception. 위반 시 points to consequences.

The question is: Who is the legal actor, what action is required or allowed, and under what condition?

하여야 한다 and 해야 한다: duty

하여야 한다 is formal legal style for “must/shall.” 해야 한다 is a plainer modern equivalent in many contexts. Both can impose obligation depending on the text.

Example structure:

신청인은 필요한 서류를 제출하여야 한다.

Actor: 신청인. Action: 필요한 서류를 제출하다. Force: duty.

Legal Korean often places conditions before the duty:

허가를 받으려는 자는 신청서를 제출하여야 한다.

The person who wants permission must submit an application. The condition defines who the duty applies to.

할 수 있다: permission, authority, discretion

In legal texts, 할 수 있다 often means “may” in the sense of permission or authority. It gives a person or agency power to act, but does not always require action.

행정청은 과징금을 부과할 수 있다.

The administrative agency may impose a penalty surcharge; the sentence grants authority or discretion. It does not say the agency must impose one in every case.

Learners must not read 할 수 있다 as simple ability. In law, permission and discretion are central.

해서는 안 된다 and 하여서는 아니 된다: prohibition

해서는 안 된다 and 하여서는 아니 된다 prohibit an action. Older or more formal statutory language often contains 하여서는 아니 된다. Plain-language legal drafting and public-facing guidance increasingly prefer shorter forms such as 해서는 안 된다 where the force remains the same.

누구든지 허가 없이 출입하여서는 아니 된다.

Actor: anyone. Prohibited action: entering without permission.

금지한다 is another direct prohibition: 흡연을 금지한다, 반입을 금지합니다. Signs and regulations often use noun-based prohibition.

다만: exception

다만 introduces an exception or qualification:

신청인은 서류를 제출하여야 한다. 다만, 이미 제출한 경우에는 그러하지 아니하다.

The exception is not a side comment. It changes the legal scope. Learners reading contracts, regulations, or terms of service should always mark 다만, 제외한다, 예외로 한다, and 경우에는.

위반 시 and consequences

위반 시 means “in case of violation.” It often introduces penalties, cancellation, restrictions, or administrative action. 시 here is a bound noun meaning time/case in formal style.

위반 시 이용이 제한될 수 있습니다.

This combines violation condition with 할 수 있다, often meaning the institution may restrict use.

Legal noun phrases are dense

Legal Korean often builds long noun phrases before the modal expression: 법령에 따른 의무를 위반한 자, 허가를 받으려는 자, 제1항에 따른 신청서, 정당한 사유 없이. The final modal phrase tells the force, but the noun phrases define who and when.

Do not translate before identifying the actor and condition.

Technical-review guardrail: this is language analysis, not legal advice

The article teaches linguistic force in Korean legal and regulatory text. It does not interpret any specific law for compliance. For actual rights, duties, deadlines, or penalties, readers must consult the current official text and a qualified professional when needed.

Remediation upgrade: legal wording must preserve force

The legal article now distinguishes older/formal statutory wording from plain-language drafting without changing legal force. 하여야 한다 and 해야 한다 can both impose duty; 하여서는 아니 된다 and 해서는 안 된다 can both prohibit; 할 수 있다 often grants authority or discretion rather than physical ability. The plain rewrite must never weaken a duty or turn discretion into obligation.

Mini practice: identify legal force

Learner workflow: legal-force routine

1. Identify the actor: who must, may, or must not act.
2. Identify the action phrase.
3. Identify the force: duty, permission, prohibition, application, exception, consequence.
4. Mark conditions before the actor or action.
5. Mark exceptions introduced by 다만 or 경우에는.
6. Translate 할 수 있다 as legal permission/discretion when context requires, not as physical ability.

Suggested functions:

1. Clause input: user enters a regulation or terms-of-service sentence.
2. Actor/action labels: highlights duty-holder and action.
3. Force classifier: obligation, permission, prohibition, exception, consequence.
4. Condition mapper: identifies if/when phrases and 다만 clauses.
5. Plain-Korean rewrite: paraphrases dense legal Korean without changing force.
6. Risk notice: reminds users not to treat the tool as legal advice.

Final rule

In Korean legal text, the modal phrase is the force of the sentence. Find who acts, what action is at issue, and whether the law says must, may, must not, applies, excepts, or penalizes.