diff --git a/docs/architecture/adr-0016-diploma-eligibility-dmn.md b/docs/architecture/adr-0016-diploma-eligibility-dmn.md
index af5e19c..1e8f9d5 100644
--- a/docs/architecture/adr-0016-diploma-eligibility-dmn.md
+++ b/docs/architecture/adr-0016-diploma-eligibility-dmn.md
@@ -1,4 +1,4 @@
-# ADR-0016: Diploma eligibility is a DMN evaluated inline as a BPMN businessRuleTask
+# ADR-0016: Diploma eligibility is a DMN evaluated inline as a BPMN DMN service task
 
 - **Status:** Accepted
 - **Date:** 2026-07-17
@@ -22,14 +22,16 @@ back. That is one option; it is not the only one, and it is not the cleanest.
 ## Decision
 
 **The diploma-eligibility DMN is deployed to Flowable and evaluated inline by the registratie process
-as a `businessRuleTask`; an exclusive gateway routes on its output. The domain's only new job is to
-carry the diploma origin and pass it into the process as a start variable.**
+as a DMN service task (`flowable:type="dmn"`); an exclusive gateway routes on its output. The domain's
+only new job is to carry the diploma origin and pass it into the process as a start variable.**
 
 - **The decision lives in the workflow.** `workflows/diploma-eligibility.dmn` maps `diplomaOrigin`
-  → `route` (`Buitenlands` ⇒ `CBGV_ADVIES`, otherwise `DIRECT`). A `businessRuleTask`
+  → `route` (`Buitenlands` ⇒ `CBGV_ADVIES`, otherwise `DIRECT`). A DMN service task
   (`flowable:type="dmn"`, `decisionTableReferenceKey=diploma-eligibility`) runs it between
   `OpenZaakAanmaken` and `Beoordelen`, and an exclusive gateway sends `CBGV_ADVIES` through a new
-  `CBGVAdvies` user task before `Beoordelen`, `DIRECT` straight there.
+  `CBGVAdvies` user task before `Beoordelen`, `DIRECT` straight there. (A `businessRuleTask` would
+  bind Flowable's legacy Drools/KIE implementation, which `flowable-rest` does not bundle — its parse
+  handler throws `NoClassDefFoundError` at deploy time; the DMN service task is the supported route.)
 - **The domain carries the input, not the decision.** The `Registration` aggregate gains a
   `DiplomaOrigin` (Binnenlands/Buitenlands); `SubmitRegistration` passes it to
   `StartRegistrationProcessAsync`, which sets it as the `diplomaOrigin` start variable. The domain
@@ -52,7 +54,7 @@ carry the diploma origin and pass it into the process as a start variable.**
 
 - Deviates from #14's literal "evaluated by the Domain Service via Workflow Client" wording (noted on
   the issue). The outcome — DMN decides eligibility, foreign diplomas get the CBGV step — is unchanged.
-- The DMN and its `businessRuleTask` wiring are validated live (verify-domain drives a foreign
+- The DMN and its service-task wiring are validated live (verify-domain drives a foreign
   registration through CBGV-advies and a domestic one straight to beoordeling, exercising both
   branches), not in unit tests — consistent with ADR-0009/0014/0015. The domain unit/acceptance tests
   cover only that the origin is carried into the process.
diff --git a/docs/demo-script.md b/docs/demo-script.md
index d2fcacb..436fbcb 100644
--- a/docs/demo-script.md
+++ b/docs/demo-script.md
@@ -346,7 +346,7 @@ candidate group behandelaar → teamlead (§8.2).
 
 ## S-13 — Diploma-eligibility: foreign diplomas route through CBGV-advies (#14, ADR-0016)
 
-A registration's diploma origin decides its route. A DMN `businessRuleTask` in the registratie
+A registration's diploma origin decides its route. A DMN service task in the registratie
 process evaluates the `diploma-eligibility` decision on the `diplomaOrigin` start variable: a
 **foreign** (Buitenlands) diploma is routed through an extra **CBGV-advies** user task before
 beoordeling; a **domestic** (Binnenlands) one goes straight to beoordeling. The decision lives in the
@@ -376,7 +376,7 @@ curl -s -u rest-admin:test -X POST "$FL/runtime/tasks/$TID" \
 ```
 
 **The path:** domain sets the `diplomaOrigin` start variable → registratie process DMN
-`businessRuleTask` sets `route` → exclusive gateway → foreign: `CBGVAdvies` user task → `Beoordelen`;
+DMN service task sets `route` → exclusive gateway → foreign: `CBGVAdvies` user task → `Beoordelen`;
 domestic: `Beoordelen` directly (§8.2, ADR-0016).
 
 > The domestic/foreign paths are covered by the `Een diploma op herkomst routeren` acceptance
diff --git a/infra/docker-compose.yml b/infra/docker-compose.yml
index 357b675..6c87c92 100644
--- a/infra/docker-compose.yml
+++ b/infra/docker-compose.yml
@@ -270,7 +270,7 @@ services:
         until curl -sf -u rest-admin:test "$$base" >/dev/null 2>&1; do echo "waiting for flowable-rest..."; sleep 3; done
         # Deploy the diploma-eligibility DMN via the process repository: the flowable-rest image embeds
         # the DMN engine but does not expose the dmn-api app, so the process deployment cross-deploys the
-        # .dmn resource to the DMN engine, where the registratie businessRuleTask resolves it by key
+        # .dmn resource to the DMN engine, where the registratie DMN service task resolves it by key
         # (S-13, ADR-0016).
         if curl -s -u rest-admin:test "$$base?name=diploma-eligibility" | grep -q '"name":"diploma-eligibility"'; then
           echo "diploma-eligibility already deployed; skip"
diff --git a/infra/flowable/docker-compose.yml b/infra/flowable/docker-compose.yml
index b29ff3c..3662f5c 100644
--- a/infra/flowable/docker-compose.yml
+++ b/infra/flowable/docker-compose.yml
@@ -51,7 +51,7 @@ services:
         until curl -sf -u rest-admin:test "$$base" >/dev/null 2>&1; do echo "waiting for flowable-rest..."; sleep 3; done
         # Deploy the diploma-eligibility DMN via the process repository: the flowable-rest image embeds
         # the DMN engine but does not expose the dmn-api app, so the process deployment cross-deploys the
-        # .dmn resource to the DMN engine, where the registratie businessRuleTask resolves it by key
+        # .dmn resource to the DMN engine, where the registratie DMN service task resolves it by key
         # (S-13, ADR-0016).
         if curl -s -u rest-admin:test "$$base?name=diploma-eligibility" | grep -q '"name":"diploma-eligibility"'; then
           echo "diploma-eligibility already deployed; skip"
diff --git a/infra/run-domain-check.sh b/infra/run-domain-check.sh
index 409ea76..814683d 100755
--- a/infra/run-domain-check.sh
+++ b/infra/run-domain-check.sh
@@ -159,7 +159,7 @@ done
 echo "OK — withdrawal cancelled the Beoordelen task; the registratie process ended (ingetrokken)"
 
 # ── S-13: diploma-eligibility routing. A registration with a FOREIGN diploma must route through the
-# extra CBGVAdvies user task before Beoordelen (the DMN businessRuleTask sets route=CBGV_ADVIES and the
+# extra CBGVAdvies user task before Beoordelen (the DMN service task sets route=CBGV_ADVIES and the
 # gateway branches, ADR-0016). The domestic DIRECT path is already proven by the first registration
 # above, which parked straight at Beoordelen. ──────────────────────────────────────────────────────
 cbgv_query='{"processDefinitionKey":"registratie","taskDefinitionKey":"CBGVAdvies","includeProcessVariables":true}'
diff --git a/workflows/diploma-eligibility.dmn b/workflows/diploma-eligibility.dmn
index 4dde9c2..de6e5cc 100644
--- a/workflows/diploma-eligibility.dmn
+++ b/workflows/diploma-eligibility.dmn
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!-- Diploma-eligibility decision (S-13, ADR-0016). Evaluated inline by the registratie process as a
-     BPMN businessRuleTask: given the diploma's origin, it sets the `route` the process should take.
+     BPMN DMN service task: given the diploma's origin, it sets the `route` the process should take.
      A foreign (Buitenlands) diploma routes through the extra CBGV-advies assessment step; a domestic
      one (or anything else) goes DIRECT to beoordeling. FIRST hit policy: the foreign rule wins, and
      the empty-input catch-all is the default. -->
diff --git a/workflows/registratie.bpmn b/workflows/registratie.bpmn
index 8180567..360297e 100644
--- a/workflows/registratie.bpmn
+++ b/workflows/registratie.bpmn
@@ -22,9 +22,9 @@
        (BeoordelingEscaleren); the Workflow Client reassigns the still-open Beoordelen task from the
        behandelaar group to teamlead (ADR-0015). The Beoordelen task stays open throughout — the timer
        only changes who may claim it.
-       S-13 adds diploma-eligibility routing: between OpenZaakAanmaken and Beoordelen a DMN
-       businessRuleTask evaluates the `diploma-eligibility` decision on the diplomaOrigin start
-       variable; an exclusive gateway routes a foreign diploma through the CBGV-advies user task
+       S-13 adds diploma-eligibility routing: between OpenZaakAanmaken and Beoordelen a DMN service
+       task (flowable:type="dmn") evaluates the `diploma-eligibility` decision on the diplomaOrigin
+       start variable; an exclusive gateway routes a foreign diploma through the CBGV-advies user task
        before Beoordelen, a domestic one straight there (ADR-0016). -->
   <message id="Message_Ingetrokken" name="RegistratieIngetrokken"/>
 
@@ -40,17 +40,19 @@
 
     <sequenceFlow id="flow2" sourceRef="OpenZaakAanmaken" targetRef="DiplomaEligibiliteit"/>
 
-    <!-- S-13: evaluate the diploma-eligibility DMN inline (ADR-0016). Flowable runs the deployed
-         `diploma-eligibility` decision against the diplomaOrigin start variable and sets the `route`
-         output as a process variable. The gateway then routes a foreign diploma through CBGV-advies,
-         a domestic one straight to Beoordelen. -->
-    <businessRuleTask id="DiplomaEligibiliteit" name="Diploma-eligibiliteit bepalen" flowable:type="dmn">
+    <!-- S-13: evaluate the diploma-eligibility DMN inline (ADR-0016). A Flowable DMN service task
+         (flowable:type="dmn" — NOT a businessRuleTask, whose default implementation is the legacy
+         Drools/KIE one that flowable-rest does not bundle) runs the deployed `diploma-eligibility`
+         decision against the diplomaOrigin start variable and sets the `route` output as a process
+         variable. The gateway then routes a foreign diploma through CBGV-advies, a domestic one
+         straight to Beoordelen. -->
+    <serviceTask id="DiplomaEligibiliteit" name="Diploma-eligibiliteit bepalen" flowable:type="dmn">
       <extensionElements>
         <flowable:field name="decisionTableReferenceKey">
           <flowable:string><![CDATA[diploma-eligibility]]></flowable:string>
         </flowable:field>
       </extensionElements>
-    </businessRuleTask>
+    </serviceTask>
 
     <sequenceFlow id="flow2a" sourceRef="DiplomaEligibiliteit" targetRef="RouteOpDiploma"/>