Inversion of Control

A wet (formal law) often leaves specifics to someone else. The Healthcare Allowance Act delegates setting the standard premium to the minister, whose ministerial regulation sits below the act. The Participation Act leaves the reduction of social assistance to municipal ordinances, but that is co-government (medebewind): the act calls on the municipality to execute it through its own ordinance. The municipality is not administratively subordinate to the state, but its ordinance is still bound by the act and yields to it (Gemeentewet art. 121-122).

In RegelRecht, both relationships are modeled through the same two constructs: the law declares an open term (a value it needs but does not define), and the regulation that fills it declares that it implements that term.

The legal pattern

A Dutch ministerial regulation typically opens with a preamble: “Gelet op artikel 4 van de Wet op de zorgtoeslag” (“In consideration of article 4 of the Healthcare Allowance Act”). The preamble records which article the regulation rests on; the power itself comes from that article of the law, not from the preamble. Consolidated texts on wetten.overheid.nl show only the preamble of the original regulation, so a later amendment on a new basis does not show there.

RegelRecht mirrors the direction. The law does not need to know which regulation fills its open term. The implementing regulation registers itself.

How it works

The law declares an open term

# Zorgtoeslagwet, article 4 machine_readable: open_terms: - id: standaardpremie type: amount required: true delegated_to: minister delegation_type: MINISTERIELE_REGELING legal_basis: artikel 4 Wet op de zorgtoeslag default: actions: - output: standaardpremie value: 211200

This says: “I need a value called standaardpremie. The minister should set it via a ministerial regulation. If nobody has set it, use 211200 (EUR 2,112.00).”

Two optional fields say more about who fills the term, and both are properties of the law rather than of the corpus:

expected_source names the regulation the article itself points at, such as Regeling zorgverzekering, with a BWB id when the text carries one. Whether that regulation is currently in the corpus is a separate question, because that changes without the law changing.
decided_per_case_by names the authority that fills the norm in the individual case while no general specification exists, with the article making it competent. That answer needs a motivation under Awb 3:46 and forms part of the besluit rather than a ground for it, which is what separates a discretionary power from a value that is merely missing.

The implementing regulation fills it

# Regeling standaardpremie, article 1 # regulatory_layer: MINISTERIELE_REGELING # valid_from: 2025-01-01 machine_readable: implements: - law: wet_op_de_zorgtoeslag article: '4' open_term: standaardpremie gelet_op: Gelet op artikel 4 van de Wet op de zorgtoeslag execution: output: - name: standaardpremie type: amount type_spec: unit: eurocent actions: - output: standaardpremie value: 211200

The gelet_op field matches the real legal preamble text. The implements block tells the engine: “I fill in the standaardpremie open term from Zorgtoeslagwet article 4.”

The engine connects them at load time

When the engine loads all ruleworks, it builds an index of all implements declarations. When it encounters an open_term during execution, it looks up the index, finds the implementing regulation, and executes it to get the value.

Municipal ordinances (co-government)

The Participation Act leaves the reduction of social assistance to municipal ordinances, in co-government. The schema records this with delegated_to and delegation_type, the same fields it uses for delegation, although legally it is not delegation. Each municipality can set different reduction percentages. The engine uses gemeente_code in the execution parameters to select the right municipal ordinance.

The national law declares open terms with defaults

# Participatiewet, article 8 machine_readable: open_terms: - id: verlaging_percentage type: number required: true delegated_to: gemeenteraad delegation_type: GEMEENTELIJKE_VERORDENING legal_basis: artikel 8 lid 1 onderdeel a Participatiewet default: actions: - output: verlaging_percentage value: 0

The default of 0 follows the legal logic: article 18(2) says “reduces in accordance with the ordinance.” No ordinance means no reduction.

A municipality implements the open term

# Afstemmingsverordening Participatiewet Diemen, article 9 # regulatory_layer: GEMEENTELIJKE_VERORDENING # gemeente_code: GM0384 machine_readable: implements: - law: participatiewet article: '8' open_term: verlaging_percentage gelet_op: Gelet op artikel 8, eerste lid, onderdeel a van de Participatiewet

When executing for a person in Diemen (parameters include gemeente_code: GM0384), the engine uses Diemen’s percentages. For a municipality without an ordinance, the Participation Act’s default applies.

An implementation that reads the law it fills in

An implementation can state its value in terms of the law it fills in. A ministerial regulation indexing an amount is the common case: “het in artikel 4 genoemde bedrag wordt met ingang van 1 januari verhoogd met 3,2 procent”, where the law leaves the amount open with a default. The implementing article then reads an output of that law, which depends on the very term it fills. That read is the law without this filling: the next implementation, or the default when there is none. The filling then applies once, whether the law or the implementing regulation is asked.

A reduction that fills an open term

A cell’s reduction (RFC-048) may name an open term with implements too (schema v0.8.5). It is not a regulation: it reads the cell’s own decisions back, and only the cell runs it. Art. 13a of the Leerplichtwet 1969 leaves verlof_al_verleend_in_schooljaar to the head per case (decided_per_case_by), and the school’s reduction fills it:

# reductie_verlof_al_verleend_in_schooljaar, article 1 # regulatory_layer: REDUCTIE machine_readable: implements: - law: leerplichtwet_1969 article: 13a open_term: verlof_al_verleend_in_schooljaar

The engine does not run it. A caller can pass an answerer with the execution (OpenTermAnswerer, in a Call). The engine asks it first for every open term an article reads, at any depth. That includes an article called anew, as Awb 7:11 does on an objection. During a decision the cell is that answerer: it runs its reduction with the parameters the reduction declares, taken by name from the article that declares the term, and returns the value with where it came from. The engine records that provenance under open_terms (filled_by: {answer: ...}) and as one node in the trace. Why the reduction answered as it did is the cell’s to explain (Cell::explain_answer); it is not in the trace of the decision. A REDUCTIE is never in the engine’s implements index, so loading one changes nothing by itself.

The order of precedence is the one for every open term: the answerer, then an implementation, then the finding of the authority for the case, then the default. A required term that has no default, and that none of these fills, is an error; a term that is not required then resolves to null. Outside a cell there is no answerer, so a scenario gives the head’s finding.

Conflict resolution

When multiple regulations implement the same open term, the engine resolves conflicts using two rules from legal theory:

Lex superior (higher regulatory layer wins): a wet takes precedence over a ministeriële regeling, and an ordinance yields to the act it executes
Lex posterior (newer wins): between two regulations at the same level, the one with the later valid_from date takes precedence

Temporal filtering ensures the right version applies: only regulations where valid_from <= calculation_date are considered.

Comparison with cross-law references

Cross-law references and IoC both let laws use values from other laws, but they serve different purposes:

	Cross-law reference	Inversion of Control
Who knows whom?	The referencing law names the target law	The law does not know which regulation fills its open term
Direction	Top-down: “give me this value from that law”	Bottom-up: “I fill in this value for that law”
Use case	A law needs a specific value from a specific other law	A law leaves a value to whichever regulation fills it, by delegation or in co-government
YAML construct	`source: { regulation: ..., output: ... }`	`open_terms` + `implements`