Bloodline Over Ballot: What Japan’s Succession Law Teaches Indian Family Law

*Pranay Rajesh Sonkusare

On 17 July 2026, Japan’s Parliament enacted a revised Imperial House Law, the country’s first major amendment to succession rules in decades. The law was passed under Sanae Takaichi, Japan’s first ever female Prime Minister, who told Parliament months earlier that she personally endorses the position that succession should remain limited to male-line male descendants. The revision expands the pool of men eligible to succeed by allowing the imperial family to adopt distant male relatives from now-defunct collateral branches, and lets princesses retain their royal status after marrying commoners. What it does not do is give any woman, including the emperor’s only child, Princess Aiko, a right to succeed. A female head of government has just presided over legislation that hardens, rather than loosens, the exclusion of women from her country’s oldest institution. This is not a contradiction but rather a demonstration of what happens when succession law is built to sit outside the reach of an equality guarantee.

A Constitutional Carve-Out, Not An Oversight

Japan’s exclusion of women from the throne is not merely a policy choice reflected in ordinary legislation, the kind of provision that could, in principle, be amended by a simple parliamentary majority. The Constitution itself insulates that choice from ordinary politics: Article 2 delegates the entire question of succession to the Imperial House law, and it is that statute, not the constitutional text, which contains the substantive male-only rule. Article 2 of Japan’s Constitution provides that ‘the Imperial Throne shall be dynastic and succeeded to in accordance with the Imperial House Law passed by the Diet.’ This single sentence does two things. First, it delegates the entire question of succession to ordinary legislation. Second, it does so from a distinct constitutional chapter, one concerned with the emperor as a symbol of the state, rather than from the chapter containing Japan’s equality guarantee. Japan’s own Diet has treated this much as settled: the House of Representatives’ Research Commission on the Constitution has recorded cross-party agreement that Article 2 is an ‘exceptional provision’ that the Constitution itself permits. What has never been settled is whether Article 14’s equality guarantee should be read into it, a disagreement the Commission has acknowledged for over two decades without resolving. The practical result is a succession rule that has never needed to survive a rights challenge, because no institution, legislative or judicial, has ever been forced to answer the question that the text leaves open.

A government panel reached the same conclusion in 2021, recommending no change to the male-only rule, and Takaichi has now enacted legislation consistent with that recommendation despite recorded public sympathy for Princess Aiko’s succession, a Kyodo News poll taken two months before the vote found 83 per cent support for allowing a female emperor, against the 13.1 per cent that opposed it, reported widely in coverage of the family’s shrinking numbers. The law’s one soft hinge is a supplementary provision requiring the statute to be reviewed once every thirty years. That is not nothing: it leaves room, at least formally, for the debate to resurface. But a scheduled review is not a right, and nothing compels a different outcome next time either.

India’s Opposite Trajectory: From Personal Law Immunity To Vineeta Sharma

India inherited its own deeply patrilineal succession tradition in the Mitakshara coparcenary, under which only male descendants held a birth right in the ancestral property. For decades, Indian courts treated personal law, including Hindu Succession law, as substantially insulated from ordinary constitutional equality scrutiny, an assumption traceable to the Bombay High Court’s reasoning in State of Bombay v. Narasu Appa Mali (1951) that uncodified personal law was not ‘law’ within the meaning of Article 13. Unlike Japan’s succession rule, the insulation never constitutionally entrenched the way Article 2 entrenches the Imperial House Law. It was a judicial and legislative assumption, and assumptions of that kind can be legislated around, as done by the Parliament.

The Hindu Succession (Amendment) Act, 2005, amended Section 6 of the Hindu Succession Act, 1956 and provided that daughters are coparceners by birth and are given equal rights and liabilities as sons. However, the amendment’s text did not make clear whether a daughter’s coparcenary rights depended on her father having been alive on the date the amendment came into force, and different benches of the Supreme Court in Prakash v. Phulavati (2015) and Danamma v. Amar (2018)  gave conflicting answers to this question for years: Phulavati held that a daughter’s right depended on her father being alive when the amendment came into force, while Danamma reached the opposite practical outcome even though the father in that case had died decades earlier. The Court finally answered this question in Vineeta Sharma v. Rakesh Sharma (2020). The Court held that the 2005 amendment applies retroactively: a daughter becomes a coparcener by birth regardless of whether her father, the family member through whom her claim arises, was alive when the amendment came into force. Unlike a specific inherited asset, coparcenary status does not depend on the ancestor being alive at any particular moment; it exists from birth. The judgment did not need to invoke Article 14 to reach a gender-egalitarian result. But the interpretive move it made, refusing to let an accident of timing determine whether a daughter counts as a full heir, only makes sense against a background assumption: that succession law answers to constitutional values of equal treatment. Japan’s constitutional design forecloses that same assumption from the outset for its imperial succession.

Not Every Personal Law Has Had Its Vineeta Sharma Moment

This rewrite of Hindu Succession law did not happen because Parliament or the courts abstractly decided that patrilineal inheritance was unfair. The reason for this is that litigants had been forcing the question in Prakash v. Phulavati (2015) and Danamma v. Amar (2018) for years prior to the closure by Vineeta Sharma. But it was litigation, and not legislative goodwill or scheduled review that got this body of law to that point, and that is an outcome Japan's 30-year review clause is meant to guard against.

Other Indian personal law systems are still waiting for their own forcing event. Classical Sunni inheritance rules, applied through the Muslim Personal Law (Shariat) Application Act, 1937, give a daughter half or even less of the share a son receives on intestate succession, a rule that has sat undisturbed behind the same Narasu Appa Mali logic that once shielded Hindu coparcenary. That rule is now being tested: in April 2026, the Supreme Court issued notice to the Union on a writ petition by advocate Poulomi Pavini Shukla (Poulomi Pavini Shukla v. Union of India (2025)) and the Nyaya Naari Foundation seeking this declaration under Articles 14, 15 and 21, after the court had already remarked that a Uniform Civil Code was the answer, and that striking the 1937 Act down risked a legal vacuum. That is a Court doing to a live equality claim something analogous to what Article 2 does to Japan’s succession by design: both route the question toward the legislature rather than resolve it as a matter of rights. The difference is that India’s version of this insulation was never entrenched the way Japan’s is, so the door is not sealed forever. But as of this writing, nobody has forced it open; the petition remains pending, tagged with similar matters, with no date set for final hearing.

What Representation Alone Does Not Do

The comparison matters for a reason beyond doctrinal curiosity. It is tempting to treat descriptive representation, a woman occupying the office of Prime Minister, as a proxy for substantive progress on gendered law. Takaichi’s succession law is a clean counter-example: representation at the top of government did not translate into representation within the office of head of state, because the legal structure governing that office was never built to be moved by who happens to hold political power at a given moment. Structural insulation from rights review beats the preferences of whoever is in office, female or otherwise.

India’s experience cuts the other way but should not be read too triumphantly. Constitutional and judicial pressure, applied over sixty years, did eventually reach even a body of law once treated as untouchable. But that pressure has been radically uneven. Muslim and other personal law systems, remain far less reformed than Hindu succession law, and the same Narasu Appa Mali assumption that took decades to erode for Hindu coparcenary continues to shield large parts of Indian family law from the scrutiny Vineeta Sharma eventually applied. Japan is close to what complete constitutional insulation looks like, the review clause is a formal escape hatch, not a right. In India the demolition of insulation has been demonstrated but only sporadically, over time, and through the efforts of persistent litigation. Neither system suggests that equality in succession follows automatically from having women in a position of power. In both, equality follows only from building, or dismantling, the specific legal architecture that determines whether succession rules can be challenged at all.

A Note For Family Law Reform Generally

The lesson is not that Indian family law has solved the question that has eluded Japan. It is rather about the means as well as the result. But wherever a succession rule, whether dynastic, coparcenary, or customary is designed to be beyond the reach of an equality clause, representation in the government is unlikely to reliably affect it, because those represented have nowhere to challenge it. A Vineeta Sharma moment, for any given personal law system, arrives only when a litigant is willing to spend years testing the question and a court is willing to treat old assumptions as revisable. These are the same two ingredients, over decades, shifted Hindu succession law away from the assumption traceable to Narasu Appa Mali and toward the gender-equal outcome eventually reached in Vineeta Sharma, and that the Muslim Personal Law challenge now before the Supreme Court has not yet supplied in combination.

The Diet closed a door in July that Indian courts spent decades prying open for one community, and have not yet reached for several others.

*Pranay Rajesh Sonkusare is a second- year law student pursuing B.Sc. LL.B.(Hons.) at West Bengal National University of Juridical Sciences, Kolkata.

The views expressed above are the author's alone and do not represent the beliefs of Family Law Chronicle: The CFL Blog.