A summer camp run by a university club. A woman pressed to keep drinking finds herself in another room. She never manages a spoken “no”; she cannot even force a smile, only freeze. The next morning she goes home unsure whether she consented at all. For a long time, such situations were treated legally as “consent” and held hard to prosecute. The demand for sexual consent as a norm that sharply separates the appearance of consent from real consent is recent.

Sexual consent (性的同意, English affirmative consent, yes means yes) is the state of free, voluntary agreement by both parties that is required for a sexual act to be legally and ethically justified. Its elements are that the parties can form, express, and sustain their intention, that there is no interference by force, fear, confusion, or intoxication, and that consent can be withdrawn at any point during the act. This article covers the concept’s structure, its history, the Japanese statutory developments, international comparison, and the educational points.

Structure of the concept

Consent is not captured by a single yes or no. Legal, ethical, and psychological work has drawn out four elements: capacity (judgement not impaired by age, disability, intoxication, or drugs); voluntariness (no force, threat, or coercion by position); expression (an explicit verbal or behavioural showing of intention); and continuity (consent sustained, not withdrawn, throughout). If even one element is missing, no valid consent exists despite the absence of overt refusal. A “yes” from a heavily intoxicated person is void for lack of capacity; silence before a superior’s advance is suspect for voluntariness. The concept makes these fine elements visible, narrowing the room for a perpetrator to claim “I wasn’t refused”.

History

In pre-modern Western law and old Japanese law, sex crime was framed not as a violation of the victim’s will but as injury to the “honour of the house”, “marital right”, or “chastity” under patriarchy. The 1880 old Penal Code’s rape offence required “violence or threat” rather than the victim’s consent, with the victim’s resistance the key to prosecution; comparable structures ran through nineteenth-century Western criminal law. The second-wave feminist movement (1960s–1970s) reframed sex crime around the individual’s sexual autonomy; Susan Brownmiller’s Against Our Will (1975) and Susan Estrich’s Real Rape (1987) made visible the judicial invisibility of sex crime lacking violence or threat. From the 1990s, campus anti-violence movements advanced the “affirmative consent” (yes means yes) principle, asking not whether the victim refused but whether the actor confirmed positive consent; California’s SB-967 (2014) required affirmative-consent standards at state higher-education institutions, with similar legislation following.

Japanese statutory developments

The former forcible sexual intercourse offence (pre-2023 Article 177) long required “violence or threat”, leaving abuse of position, exploitation of intoxication, and abusive-relationship cases hard to prosecute. The 2017 amendment renamed the offence, made it gender-neutral, and added oral and anal penetration, but kept the force element. The 2023 amendment (in force 13 July 2023) created the non-consensual sexual intercourse offence, placing a “state in which it is difficult to form, express, or sustain a non-consenting intention” at the centre and listing eight causes (violence or threat; mental or physical disorder; alcohol or drugs; sleep or clouded consciousness; no time to refuse; fright or astonishment at an unexpected situation; a psychological reaction from abuse; the influence of position). Prosecution became possible where, without violence or threat, the victim was unable to express refusal. The same amendment raised the age of consent from 13 to 16, with a five-year age-gap rule for those 13 to under 16, addressing a consent age long flagged by international bodies as conspicuously low.

International comparison

In the US the affirmative-consent principle spread at state and university level, from California’s SB-967 (2014) to New York’s Enough is Enough Act (2015), with Title IX imposing harassment- and violence-prevention duties on higher education. The UK Sexual Offences Act 2003 centres the absence of consent, defining consent as agreement “by choice with the freedom and capacity to make that choice” and listing factors negating its validity, a model for later legislation. Sweden’s 2018 consent law (samtyckeslag) criminalises sex without explicit consent even absent force or threat; Germany’s 2016 amendment introduced the “no means no” principle. The Istanbul Convention (in force 2014) Article 36 obliges states to criminalise non-consensual sexual acts, and CEDAW has repeatedly urged Japan to raise the age and revise the force element.

Education and movements

From the 2010s, sexual-consent workshops spread in Japanese universities and high schools, run at orientation and by student groups and Spring, teaching equal relations in sexual activity as well as preventing harm. UNESCO’s guidance places consent at the core of sex education, but the Japanese curriculum does not list it as an independent topic, leaving classroom coverage dependent on NGO supplementation. The recognition of the freeze response (tonic immobility), reported in around 70 per cent of sexual-violence victims in a 2017 Karolinska Institute study by Möller and colleagues, informed the inclusion of “fright or astonishment at an unexpected situation” among the non-consent causes.

Points of debate

The move to a consent-centred structure burdens the courts with proving the victim’s subjective state, with disagreement between the parties’ perceptions liable to become the issue and a risk of secondary harm; prompt reporting, objective records, and specialist medical certificates support the case in practice. The “grey zone”, where overt force is absent and the parties’ readings of consent differ, raises the question of where to draw the line between criminal and civil or social responsibility. There is an argument that the “yes means yes” principle, demanding explicit confirmation, creates friction in cultures emphasising non-verbal and contextual communication; education works to convey the core of consent (free will, equal relations) within the cultural context.

See also

• Non-consensual sexual intercourse offence
• Forcible sexual intercourse offence
• Waisetsu
• Sexual harassment
• Sex education
• Age of consent