The ongoing debate regarding Bitcoin and quantum computing often becomes muddled as participants conflate two distinct issues.

One aspect pertains to the technical implications: Should quantum computing advance to the point where it can undermine Bitcoin’s signature scheme, the protocol has the capacity to adapt. This may include new address types, migration rules, soft forks, deprecations, and key rotation. While this constitutes a significant engineering challenge, it remains an engineering problem.

The second aspect centers on legal concerns: Should an individual utilize a quantum computer to derive a private key for an inactive wallet and subsequently access the coins, the legal ramifications must be elucidated. Is this action viewed as the recovery of abandoned property, or is it regarded as theft?

In April 2026, BIP-361 was proposed, seeking to freeze over 6.5 million BTC stored in quantum-vulnerable unspent transaction outputs (UTXOs), including an estimated one million coins linked to Satoshi Nakamoto. This issue has transitioned from theoretical discourse to a tangible conflict concerning ownership, confiscation, and the interpretation of property within a framework that fundamentally acknowledges control.

The author does not assert a position regarding the timeline for the emergence of a quantum computer capable of threatening Bitcoin. Rather, the pressing question is: If such a circumstance arises, and an individual commences transactions using quantum-derived keys from long-dormant coins, how will the legal system categorize this action—legitimate recovery or theft?

Classical property law provides a rather straightforward answer: it constitutes theft.

This interpretation may provoke frustration among Bitcoin enthusiasts, as the asset itself does not uphold ownership in the manner courts typically do; it enforces control. If an individual can present a valid transaction, the network acknowledges the spending. However, this distinction underscores the necessity of clearly articulating legal interpretations of the underlying actions.

In this regard, the law is not particularly enigmatic.

Old coins do not become ownerless solely due to their age.

The Actual Quantum Risk

It is prudent to begin with a more focused, realistic understanding of the threat. Not all Bitcoin is equally susceptible to quantum risks. Generally, an address does not expose the public key until the owner initiates a transaction. This distinction is crucial, as a quantum attacker cannot merely examine any untouched address on the blockchain and extract the private key.

The real threat resides within a more restricted category of outputs. Early pay-to-public-key outputs disclose the full public key on-chain. Certain older script configurations do the same. Furthermore, Taproot outputs present a direct commitment to a 32-byte output key rather than its hash. Address reuse also poses a risk, as it can expose the public key once a user conducts a transaction leaving behind funds tied to the same key. Such coins are the ones commonly referenced in discussions about exposed Bitcoin.

The timeline concerning these risks has been expedited. Research published by Google Quantum AI on March 31, 2026, indicated that Bitcoin’s secp256k1 curve could potentially be compromised using fewer than 500,000 physical qubits, a substantial reduction from earlier estimates nearing nine million. The research also models the mempool attack vector, demonstrating that during a transaction, the public key is exposed for approximately ten minutes prior to block confirmation, providing a quantum adversary the opportunity to derive the key before the transaction is confirmed.

Current quantum hardware remains significantly below these thresholds: Google’s Willow chip operates at 105 qubits and IBM’s Nighthawk at 120 qubits. However, advancements in algorithmic optimization are progressing more rapidly than hardware scaling. The National Institute of Standards and Technology (NIST) has outlined a post-quantum migration roadmap mandating the deprecation of quantum-vulnerable algorithms from federal systems by 2030, with a complete disallowance by 2035. While this federal timeline does not impose direct obligations on Bitcoin, it establishes a benchmark for institutional investors and regulators to measure the network’s preparedness.

A considerable portion of these coins are aged. Some are undoubtedly lost; others belong to deceased individuals or are entangled in paper wallets, forgotten backups, or unprocessed estates. There are also undoubtedly coins belonging to living individuals who simply choose not to engage with them.

This latter point assumes greater significance than the “lost coin” narrative typically acknowledges. Dormancy alone provides little clarity. A wallet may lie inactive for years due to a deceased owner, loss of access keys, disciplined investment strategies, paranoia, or other arrangements—such as being linked to Satoshi, who may prefer anonymity over litigation. The blockchain does not elucidate the true rationale behind the inactivity.

This uncertainty underscores why property law has never interpreted silence as a means of relinquishing ownership.

Dormancy Is Not Abandonment

The prevalent “finders keepers” sentiment circulating within these discussions bears little resemblance to the functioning of property law.

Ownership does not dissipate merely because property remains unused. Title persists until it is transferred, relinquished, extinguished by legal means, or displaced by an applicable doctrine. Time alone does not fulfill this role, nor does inaction or value.

Consequently, those arguing that dormant Bitcoin is free for the taking typically hinge their claims on abandonment. The assertion is simple: these coins have remained untouched for an extended period, hence they must be deemed abandoned.

However, the law addresses this matter with greater rigor. Abandonment generally necessitates both the intention to relinquish ownership and an act that manifests that intention. An owner must genuinely desire to give up ownership and undertake an action that evidences their intent. Merely failing to transact with an asset for an extended period is insufficient, particularly when the asset retains obvious value.

This is not merely a pedantic detail; it is a fundamental principle of property law. If nonuse sufficed to erase title, the law would implicitly invite the looting of any asset whose proprietor had remained silent for too long. This principle applies across various asset classes, including land, residences, stock certificates, buried cash, and heirlooms. The same principle holds for Bitcoin.

Consider a clear edge case: if someone purposefully sends coins to a burn address devoid of usable private keys, this may appear to demonstrate abandonment, as it includes both a definitive act and a clear signal. However, this example underscores the opposite point of what quantum raiders argue; it illustrates what intentional relinquishment looks like when genuinely executed. The majority of dormant wallets do not exhibit this characteristic.

The prevailing interpretation ought to be straightforward: old coins remain old coins. Some are lost; some are inaccessible; some are forgotten; others are merely inactive. None of this converts them to ownerless property.

Recent legislative measures have begun to solidify this understanding. The UK’s Property (Digital Assets etc) Act 2025, enacted on December 2, 2025, establishes a third category of personal property specifically addressing crypto-tokens. In the United States, UCC Article 12 has been adopted by over thirty states and the District of Columbia, explicitly recognizing “controllable electronic records” as a distinct legal category. Neither legislative framework endorses dormancy as equating to relinquishment. By categorizing digital assets as property, both frameworks raise the threshold for claims asserting that old coins are ownerless by default.

Death Does Not Erase Ownership

The next argument often shifts from abandonment to mortality. While it may be conceded that the coins were not abandoned, it is argued that many of these early holders are deceased. Does this factor influence the legal analysis?

Not in the manner proposed by those seeking ownership without recompense.

Some early wallets give rise to a Schrödinger’s-heir dilemma: the owner is pronounced deceased when convenient for the claimant to assert that property is ownerless, then regarded as notionally accessible when succession obligations come into play. Property law does not accommodate such ambiguity.

Upon an individual’s death, title does not disappear; it is transferred. Property devolves to heirs, devisees, or, absent both, escheats to the state. The law does not merely become ineffectual; it maintains the continuity of ownership even when possession becomes fraught, inconvenient, or altogether unattainable.

The analogy to tangible property is straightforward. If an individual passes away owning a ranch, the first trespasser to break in does not become the new proprietor by virtue of their boldness. The estate handles succession. In the absence of heirs, the state possesses a claim. Valuable property does not become ownerless solely due to the original owner’s demise.

Bitcoin operates under the same premise. Lost keys do not affect title; inaccessibility does not convey ownership. An individual who later derives the private key with superior technology does not uncover unowned treasure; they gain the capability to maneuver property that remains owned by another individual or estate.

This conclusion is particularly relevant for the largest subset of old, vulnerable coins: those associated with Satoshi. Whether Satoshi is alive, deceased, or perpetually withdrawn from public view does not alter the legal classification of those coins. They remain the property of either Satoshi himself or Satoshi’s estate; they do not transform into rewards for the first individual who arrives equipped with quantum tools.

Unclaimed Property Law Does Not Rescue the Theory

Some may posit that dormant Bitcoin can fall under the purview of unclaimed property law. While this perspective is understandable, it misinterprets how such statutes function.

Unclaimed property law typically transpires through a custodian. A bank, broker, exchange, or similar entity holds property on behalf of the owner. If the owner remains absent for an extended period, the state mandates the custodian to report and remit the asset, subject to the owner’s right to reclaim it at a later date. This doctrine is predicated on intermediaries.

This framework is effective for exchange balances, custodial wallets, and assets held by businesses. However, it does not apply similarly to self-custodied Bitcoin. A self-custodian’s UTXO lacks a custodian intermediary; there is no bank in between or transfer agent awaiting directives. Only the network, the key, and the individual capable of presenting a valid transaction exist.

This distinction implies that while governments can often access custodial crypto, the framework for self-custodied Bitcoin presents a more stringent limitation. The law can establish ownership; it can occasionally dictate who should surrender it, but it cannot conjure the private key.

This same obstacle undermines the more sophisticated iteration of the argument under UCC Article 12. A quantum adversary who derives the private key may effectively gain control of the asset in a practical sense; however, control does not equate to title. It has never constituted an alternative. A burglar who discovers the combination to a safe also gains control, yet retains the status of a thief.

Adverse Possession Does Not Fit, and Salvage Is Worse

Two commonly referenced analogies when seeking to legitimize quantum theft through legal doctrines are adverse possession and salvage.

Neither analogy withstands scrutiny in light of the facts.

Adverse possession, which was developed in relation to land, encompasses specific conditions that are relevant in disputes over land. Possession must be open and notorious enough to afford the true owner a reasonable opportunity to recognize the adverse claim and contest it. A quantum attacker who transfers coins to a new address does not achieve this level of openness. While the transaction may be visible on-chain, this does not constitute meaningful notice legally. A pseudonymous transaction on a public ledger does not convey to the owner who is asserting a claim or the basis of that claim.

The policy rationale foundational to adverse possession also collapses under scrutiny. This doctrine aims to resolve stale land disputes, quiet title, and reward visible use of neglected real property. Bitcoin presents none of these structural challenges, as the blockchain inherently records the chain of possession.

Salvage theory is even less applicable. Salvage rewards an entity that rescues property from peril. A quantum raider does not engage in such altruism; rather, they exploit the peril. In many instances, they may be responsible for creating the very peril in question. Labeling this behavior as “salvage” is comparable to categorizing a pirate as a lifeguard simply because they arrived with a boat: it is a euphemism masquerading as a legal theory.

What BIP-361 Is Really Fighting About

This rationale underscores the importance of BIP-361. It represents the first substantial proposal aiming to confront the issue at the consensus layer rather than deferring litigation and scholarly debate until subsequent fallout occurs.

Broadly, the proposal would be implemented in phases. Initially, users would be prohibited from transferring new Bitcoin into quantum-vulnerable address types, while still being permitted to migrate existing funds to more secure locations. Subsequently, legacy signatures from vulnerable UTXOs would be invalidated for the purposes of spending those coins. Effectively, any remaining unmigrated funds would become frozen. Additionally, a recovery mechanism utilizing zero-knowledge proofs linked to BIP-39 seed possession has been proposed, though this aspect remains aspirational and incomplete.

Importantly, the recovery mechanism is applicable exclusively to wallets generated from BIP-39 mnemonics. Earlier wallet formats, including those linked to Satoshi, lack a viable path for recovery under the current proposal. This limitation is significant, as it suggests that Phase C, as presently designed, would safeguard the property rights of more recent users while effectively extinguishing those of earlier holders. This constitutes a de facto statute of limitations imposed not by legislative action, but by a protocol modification.

The appeal of the proposal is evident. If the network identifies a category of coins poised to become the target of whomever reaches them first, it can refuse to endorse that reallocation. Essentially, this serves as a protective mechanism against theft, categorizing the quantum actor as a thief and denying them the ill-gotten gains.

However, this narrative accounts for only one facet of the situation. The other side does not vanish simply because protocol designers choose to overlook it.

Phase B does not merely deter thieves; it also incapacities bona fide owners who may be unable to migrate in time. This raises significant legal concerns because property law does not solely inquire whether a rule is well-intentioned; it also scrutinizes the implications for ownership.

Characterizing this situation as “theft” is overly simplistic. BIP-361 does not reallocate the coins to developers, miners, or any new claimants. It fails to enrich the freezer in the traditional sense of a thief’s enrichment. Nonetheless, “not theft” does not conclude the analysis. A more fitting analogy is that of conversion, or at the very least, an unsettling proximity to it. If the stipulation is that an owner had a valid transaction yesterday but will be deprived of it tomorrow—not due to a transfer of title, abandonment of assets, or a court extinguishing their claim, but simply because the network deemed those coins too hazardous to remain spendable—then the network has indeed taken measures beyond merely “protecting property rights.” It has deliberately hindered the practical exercise of some of those rights.

This dynamic complicates the legality of the freeze. Supporters may defend it as the lesser of two evils, and they may hold valid points. However, a lesser evil does not equate to legal clarity. A rule that obstructs an owner’s access to their own coins increasingly resembles forcible dispossession by consensus.

The most pronounced objections arise in the most challenging cases. Timelocked UTXOs exemplify this concern. If an owner intentionally created a timelock set to mature after the freeze date, they did not neglect or abandon their coins—they actively structured them to remain unspendable until a future date. Nevertheless, the protocol could still impose a freeze prior to that date’s arrival. Other older wallet formats present similar concerns. Given that the eventual recovery pathway hinges on BIP-39 seed possession, certain earlier wallet structures may lack any feasible path for recovery. Estates embody similar tensions in a different form; while the owner may have died, title has not dissipated. Freezing the coins does not nullify the underlying property claim; it only reflects the network’s unwillingness to acknowledge it.

Consequently, a more accurate description of Phase B is not merely as an “anti-theft rule” but rather as a confiscatory defense mechanism. It may be justified, perhaps even necessary, yet it is confounding in its effect for particular owners. The proposal does not solely favor owner over thief; in certain instances, it prioritizes one class of owners over another and regards the losses experienced by the less favored class as the collateral damage in the effort to safeguard the system.

This characterization does not render BIP-361 unlawful in an overtly straightforward sense. Consensus changes within Bitcoin do not constitute state action, rendering the takings analogy imperfect unless the government intervenes directly. However, from the perspective of private law reasoning, the conversion analogy takes on significant weight. Title may rhetorically endure while practical control is systematically undermined.

This dynamic captures the essence of the overarching quantum debate. Allowing a quantum attacker to appropriate dormant coins appears as theft, while freezing vulnerable coins via soft fork may represent the lesser evil. However, it is important to acknowledge that this response is not without material or moral implications. For some owners, particularly those with timelocked outputs, old wallet formats, or those lacking a feasible migration route, the freeze increasingly resembles confiscation.

This intricacy elevates the discussion beyond mere ethical considerations. Bitcoin obscures the distinction property law typically relies upon between title and possession. Courts can assert that a quantum raider stole coins. They can also affirm that a protocol-level freeze significantly interfered with an owner’s rights. Yet, the blockchain will only recognize the rules adopted by its economic majority.

As such, the discourse extends beyond the necessity for Bitcoin to uphold property rights during the transition to a quantum era; it encompasses the fundamental question of which property rights Bitcoin is willing to compromise to secure others.

Welcome to classical politics.

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