Assessment · Part B
Unsolved
Nineteen problems, ordered by whether they block the project, limit it permanently, are merely unsolved, or cannot be fixed at all. None of them is hidden in a footnote and none of them has been rewritten as a step on a plan.
A problem restated as a roadmap item has been answered without anyone answering it. Nothing on this page is a phase, a milestone or a next step. Where a page on this site engages a problem, the problem links to it; where none does, it says so, which is the more useful of the two statements.
Scope. This is a design document, and the list below is the part of it that argues against building the thing. Each problem carries a stable identifier so it can be cited directly - B-3 is the same problem in any conversation about this document.
How the four tiers differ
Blocking problems must be answered before anything is built; work done before they are answered may be work on a project that does not exist. Structural problems are permanent limits that no design in this category escapes. Design gaps are solvable and not yet solved. Unresolvable problems are accepted and disclosed, because the alternative to disclosing them is discovering that someone else did.
B.1 · Blocking
Four problems that must be answered before anything is built. Each of them can invalidate the project rather than delay it, and none of them is answered by building a prototype.
Anchor coverage economics are entirely unmodeled
The system's usefulness is a direct function of anchor density, and no model exists for how many anchors a metropolitan area needs, what each costs installed, who installs them, or what coverage share makes the product worth buying at all. This is the single largest unknown in the concept, and it is not a detail of the sort that resolves itself during delivery.
If the answer is 40,000 anchors per major metro, the project does not work.
The failure mode is specific: a pilot does not surface it, because a pilot buys its own anchors for its own small footprint and never meets the curve. The number that decides the project is the one nobody is forced to compute until the project has already been funded.
Coverage of the underlying problem is modeled on coverage; the cost model that would close this is listed on what to add and does not yet exist.
Nobody has been identified to pay
Three funding models, and each has a documented failure mode in an adjacent context. Offender-paid fees are widely litigated and drive non-compliance among indigent registrants, which converts a funding mechanism into a violation generator. Agency-paid requires an appropriation, and therefore competes against everything else the agency does. Site-paid asks school districts to fund public safety infrastructure out of education budgets that are not built to carry a hardware program with a maintenance tail.
All three have been tried elsewhere. None of the three has a default answer here, and the choice is not a procurement detail: it determines who the customer is, and therefore what the product has to be.
No page on this site closes this. It is named again on open questions and remains open there.
Anchor security is not specified at all
This is a genuine hole in the current specification rather than a known trade-off. Anchors are unattended field devices standing in public places and holding the current-interval enrollment set. The specification does not say what happens when one is stolen, opened, spoofed, or replaced with a hostile device of the same shape.
The consequences are not hypothetical. An attacker holding a rogue anchor can potentially harvest broadcast identifiers, or inject detections that never happened into a system whose entire value proposition is that its alerts can be believed. Anchors are also the most physically accessible attack surface in the design, which makes this the gap least likely to stay theoretical.
Being closed on anchor security. Until that specification exists and has been tested by somebody adversarial, this stays in the blocking tier.
Effectiveness cannot currently be proven, and the privacy design makes it harder to measure
This is the uncomfortable one, because it is a cost of the property the design is proudest of. A system that keeps no location history also keeps no record from which its own performance can be reconstructed. The same observation has already been made about the closest deployed analogue, by the laboratory that evaluated it [15]:
The privacy-preserving aspects of the protocol make it difficult to assess the performance of the apps in real-world populations.
If measurability is not designed in deliberately, from the start, the system is unfalsifiable - and an unfalsifiable program is fatal at reauthorization, because the hearing has no evidence to weigh and defaults to whatever the room already believed. The instrumentation has to be specified before deployment, not discovered at year three.
Engaged on evaluation. The design of the measurement is itself unbuilt.
B.2 · Structural
Four limits the system cannot address by any design. These are not gaps in the specification; they are the shape of what a proximity alert is, and they are the permanent ceiling on the concept.
Most people who offend against children are not on any registry
94.1% of child molestation arrests are of first-time sex offenders.DOJ SMART Office, SOMAPI ch. 8, restating Sandler, Freeman & Socia (2008), Psychology, Public Policy, and Law 14(4)
The DOJ SMART Office restatement of Sandler, Freeman & Socia. A Florida replication found 93.5%. [4]
They are on no registry, they wear no device, and they are invisible to this system at the moment they offend. No version of this design changes that, because the design is triggered by an enrollment the person does not have. It is the permanent ceiling on the concept's reach, and it is the first thing an informed reviewer will raise.
Modeled in full on coverage, and stated as a limit rather than a gap on what it solves.
Abuse by family and household members is undetectable here
48.6% of offenders against victims under 6 were family members, and 48.3% acquaintances - 3.1% strangers.Snyder, BJS, Sexual Assault of Young Children as Reported to Law Enforcement, NCJ 182990 (2000). NIBRS 1991-96, 12 states [3]
A proximity system cannot fire on someone who lives in the house, and it would have no basis for knowing that it should. Proximity carries information only when two people have no ordinary reason to be near each other; a parent, a step-parent, a sibling or a lodger has that reason continuously and lawfully. There is no threshold that separates abuse from family life, so the design scores this category at zero rather than at some small number.
Scored at zero, and the reason for scoring it at zero rather than low, on coverage.
Online grooming is untouched
The scenario this concept is most often described with - a groomed twelve- to seventeen-year-old - is now largely a digital-contact problem. 1.4 million online enticement reports were recorded by NCMEC in 2025. [37] Physical proximity alerting does not reach it, partially or indirectly, because an anchored zone is a fact about physical space and the contact this scenario turns on does not happen in physical space until it is already over.
Bolting on a digital component would not extend the system. It would import an entirely different and much harder legal problem: the Supreme Court struck down a ban on registrants accessing social media in 2017 the Supreme Court struck down a ban on registrants accessing social media. [7] and any design that watches a registrant's online contact runs at that holding directly.
Stated as out of reach on coverage and on open questions. Nothing on this site proposes to close it, and nothing should.
Most space has no anchors
By construction the system protects places, not people. A monitored person and a child in an unanchored location generate nothing at all - not a weaker alert, not a logged near miss, nothing. This is a deliberate trade made for buildability, and it buys the whole architecture: it is why the wearable can be simple, why there is no location history, and why the thing is fundable.
It is also a permanent coverage hole, and it should never be described as anything else. A map of anchored places is a map of where the system works, and the complement of that map is not covered by a future release.
The mechanism and its edges are on anchored zones; the arithmetic of what that leaves is on coverage.
B.3 · Design gaps
Seven problems that are solvable and not yet solved. Each has a plausible answer that nobody has written down, tested, or costed, and several of them decide whether the system is deployable rather than how well it performs.
The exigency path is the weak point in the whole privacy architecture
Every safeguard in the identity-resolution design has an exception written into it, and exceptions in this domain historically expand. The specification does not say who may invoke the exigency path, how often it may be used, what review it receives afterwards, or what happens when it is abused rather than merely used badly.
An unbounded exception is not a smaller version of the rule. It is the rule, held in reserve, and every structural claim the design makes about split custody runs through this one door.
The path itself is specified on identity and its logging on console. The limits on it are not.
Loss of signal has no good answer
Device failed, basement, or fled: at the moment the signal stops, these are indistinguishable, and the system has to choose a behavior without knowing which it is looking at. Fail-loud reproduces the false-alert catastrophe that this design exists to fix - one jurisdiction already treats a flat battery as an escape [32]. Fail-quiet reproduces the fatality sequence recorded in the federal review [31], in which alerts that fell below a threshold produced no notification at all.
The specification picks a middle position. It has no evidence that the middle position is the right one, and no method proposed for finding out.
The chosen behavior is on alert tiers. The evidence that it is correct does not exist.
Cross-jurisdiction movement is unaddressed
A monitored person crossing a state line leaves the anchor network, leaves the enrollment set, and possibly leaves the legal authority under which any of this was permitted. Interstate compacts exist for supervision. Nothing comparable exists for a scheme of this shape, and the design does not say what the receiving state is expected to run, honor, or refuse.
No page on this site closes this.
The false-alert remedy is specified but untested
The operational requirements say that a wrongly flagged person needs a named process and a correction that reaches everyone who received the original alert. Nobody has designed that correction flow, nobody has run it, and it contains one element that cannot be designed around:
An audible alert in a public place cannot be retracted from the people who heard it. A correction can reach a device. It cannot reach the memory of a stranger who looked up in a playground, and it cannot reach the person they told. The remedy that exists on paper covers the record; the harm it is meant to remedy is not in the record.
The requirement is on due process and the alert behavior that creates the exposure is on alert tiers. The flow itself is unbuilt and untested.
Class B zones are underspecified
A library, a mall, a transit station. Children are present incidentally, and so is everyone else, which is what makes the class necessary and what makes it hard. The specification says a Class B zone cannot auto-escalate to the highest tier, and then does not say what it should do instead.
Getting this wrong is costly in both directions. Too permissive and the class becomes the gap every encounter routes through; too aggressive and the system generates public alerts in the exact settings where a monitored person has the strongest ordinary reason to be present.
The classes are defined on anchored zones and the escalation ceiling on alert tiers. The behavior underneath the ceiling is not defined.
Device supply chain trust is asserted, not solved
The specification requires a named, audited backend operator, which states the requirement rather than meeting it. The published research is not encouraging about how many vendors could meet it: 70+ tested children's tracking devices - tens of millions of units - funnel through just three shared backends. [35]
Finding a vendor who genuinely controls their own stack, and demonstrating it rather than being told it, may be considerably harder and more expensive than the specification assumes.
Stykas & Solferini, Black Hat (Aug. 7, 2026)
An attacker could locate a watch, alter emergency contacts, falsify location, and activate microphones and cameras with no visible indication.
The requirement is on devices. The means of verifying it is not specified.
Liability is unassigned
When the system fails to fire and a child is harmed, or fires wrongly and someone is assaulted by a bystander who believed it, who is liable - the operator, the anchor host, the supervising agency, the state? The design does not say, and this is not a question that can be deferred to counsel later.
Liability determines insurability, and insurability determines whether the system can be deployed at all. An uninsurable program is not a program with a legal risk; it is a program that no school district will host and no agency will sign.
No page on this site closes this.
B.4 · Unresolvable
Four things to accept and disclose. Three are consequences of what the system is; the fourth is a harm the product creates in the ordinary course of working correctly.
The system is pseudonymous, not anonymous, and cannot be made anonymous
Anyone who can physically observe a person while capturing their broadcast identifier has bound the two together by direct observation. No cryptography prevents this, because nothing in the protocol is what leaked: the observation did.
The adversaries of concern here - an abuser tracing a survivor, a vigilante, the monitored person themselves - are precisely adversaries with eyes. This is disclosed rather than engineered around, because engineering around it is not available at any price.
Disclosed on identity and analyzed as an adversary capability on threat model.
Real-time alerting and true unlinkability are the same bit
A system that tells someone "this person is near you, now" has revealed that presence at that instant, to that person. The disclosure is the function. There is no arrangement of keys under which the alert arrives and the presence stays unlinkable, because they are the same fact delivered once.
The specification chooses real-time alerting and accepts pseudonymity. That is the correct choice for this system, and it is a choice - not a property that fell out of the design, and not something a later version recovers.
The trade is set out on data flow and its consequences on identity.
Post-discharge monitoring is legally unresolved and will stay that way for years
The federal circuits and the state supreme courts do not agree, and the question has been expressly left open by the court that could settle it. One circuit permits lifetime monitoring [6][10]; one state high court has held its own scheme unreasonable as applied to a person no longer under supervision; another splits by offense category. The Supreme Court held that attaching a device to track someone is a search and reserved the rest.
Any expansion beyond supervised populations is therefore a bet on which court hears the challenge. Scoping the system to people under supervision is not timidity; it is the only version of the design whose legal footing is known today.
The split, decision by decision, is on legal architecture, and the scoping decision that follows from it is on what is already law.
False security is a harm the product creates
This one is different in kind from the eighteen above it. The others are things the system cannot do. This is something the system does, to the people it is sold to protect.
A device that is silent through 94.1% of child molestation arrests are of first-time sex offenders. [4] - that is, silent through almost every offense as it occurs - may cause a parent to relax supervision that was doing more protective work than the device ever will. Attention is the control being displaced, and it is a better control. The product does not have to malfunction for this to happen; it happens when the product works exactly as specified and the person carrying it draws the ordinary inference from a thing that has never gone off.
This cannot be engineered away. It can only be counteracted in messaging, and messaging is the weakest control there is - it decays, it is restated by salespeople, it is dropped from the second brochure, and no gate in any build can hold it. It is recorded here as a harm the design creates rather than as a communications task, because that is what it is.
The coverage arithmetic that produces the silence is on coverage, and the claims the system is permitted to make are bounded on what it solves.
What this list is for
Two of these problems decide whether the project exists at all, and neither is a technical problem: the coverage economics in B-1 and the funding question in B-2. Two more decide whether it can be deployed once built: anchor security in B-3 and liability in B-15. Everything else on this page is either a permanent limit to be stated honestly or a piece of design work that has not been done.
The case for building it anyway is on what it solves, and the additions that would close the closeable entries are on what to add. Reading either of those without this page produces a more attractive document and a worse decision.
DOJ SMART Office, SOMAPI ch. 8, restating Sandler, Freeman & Socia (2008), Psychology, Public Policy, and Law 14(4)
The DOJ SMART Office restatement of Sandler, Freeman & Socia. A Florida replication found 93.5%.
Snyder, BJS, Sexual Assault of Young Children as Reported to Law Enforcement, NCJ 182990 (2000). NIBRS 1991-96, 12 states
NCMEC CyberTipline data (2025)
NCMEC attributes much of the rise to expanded mandatory reporting under the 2024 REPORT Act. This is report volume, not measured incidence.
How this works
1:16 · narrated · captioned · nothing here is sent anywhere when you press play. Prefer to read it? The transcript is below.
Transcript
| At | Section | What it says |
|---|---|---|
| 0:02 | What this page is | Nineteen problems in four tiers, none of them softened. A problem restated as a roadmap item has been answered without anyone answering it. Nothing here is a next step. |
| 0:13 | Blocking | Four problems block the project. Anchor coverage economics are unmodelled. Nobody has been identified to pay. Anchor security is unspecified. Effectiveness cannot yet be proven. |
| 0:26 | Structural | Four are permanent limits. Most people who offend are on no registry. Abuse inside a household is undetectable. Online grooming is untouched. Most space has no anchors. |
| 0:39 | Design gaps | Seven are solvable and not yet solved: the exigency exception, loss of signal, crossing a state line, the false alert remedy, class B zones, supply chain trust, and liability. |
| 0:52 | Unresolvable | Four are accepted and disclosed. The system is pseudonymous and cannot be made anonymous, and real time alerting and true unlinkability are the same bit delivered once. |
| 1:02 | The nineteenth | The last is different in kind. False security is a harm the product creates while working correctly, and it can only be counteracted in messaging, the weakest control there is. |