diff --git a/backend/app/domain/test_entity.py b/backend/app/domain/test_entity.py
index 6748d9f..fca1c03 100644
--- a/backend/app/domain/test_entity.py
+++ b/backend/app/domain/test_entity.py
@@ -83,7 +83,10 @@ VALID_TRANSITIONS: dict[TestState, list[TestState]] = {
     TestState.blue_evaluating: [TestState.blue_review],
     TestState.blue_review:     [TestState.in_review, TestState.blue_evaluating],
     TestState.in_review:       [TestState.validated, TestState.rejected, TestState.disputed],
-    TestState.disputed:        [TestState.validated, TestState.rejected],
+    TestState.disputed:        [
+        TestState.validated, TestState.rejected,
+        TestState.red_executing, TestState.blue_evaluating,
+    ],
     TestState.rejected:        [TestState.draft],
     TestState.validated:       [],
 }
@@ -627,6 +630,44 @@ class TestEntity:
         # Call self._events.append()
         self._events.append(DomainEvent("test_reopened"))
 
+    def resolve_dispute_reject(self, target: str) -> None:
+        """Resolve a ``disputed`` test by routing rework to the team at fault.
+
+        Called when the lead who originally approved flips their vote to
+        agree with the rejection. Rather than the generic terminal
+        ``rejected`` state (which forces a full draft restart for both
+        teams), the flipping lead identifies WHICH side's work needs
+        redoing — the test goes straight back to that team's active queue
+        so the other team's work is left untouched.
+
+        Args:
+            target (str): ``"red"`` or ``"blue"`` — which team must redo work.
+
+        Returns:
+            None
+        """
+        target_state = TestState.red_executing if target == "red" else TestState.blue_evaluating
+        self._transition(target_state)
+
+        # Both leads must re-vote once the test reaches in_review again —
+        # clear decisions but keep notes (context for the team doing rework).
+        self.red_validation_status = None
+        self.red_validated_by = None
+        self.red_validated_at = None
+        self.blue_validation_status = None
+        self.blue_validated_by = None
+        self.blue_validated_at = None
+        self.paused_at = None
+
+        if target == "red":
+            self.red_started_at = datetime.utcnow()
+            self.red_paused_seconds = 0
+        else:
+            self.blue_started_at = datetime.utcnow()
+            self.blue_paused_seconds = 0
+
+        self._events.append(DomainEvent("dispute_resolved_to_rework", {"target": target}))
+
     # -- Private -------------------------------------------------------
 
     def _auto_resume(self) -> int:
@@ -694,7 +735,14 @@ class TestEntity:
 
     # Define function _check_dual_validation
     def _check_dual_validation(self) -> None:
-        """Advance the test state once both leads have voted."""
+        """Advance the test state once enough leads have voted.
+
+        A genuine conflict (one lead's *recorded* decision disagreeing with
+        the other's) routes to ``disputed`` — there are two opinions to
+        reconcile. A lone rejection while the other side hasn't voted yet
+        isn't a conflict (nothing to disagree with), so it still vetoes
+        straight to ``rejected`` without waiting for the second vote.
+        """
         r, b = self.red_validation_status, self.blue_validation_status
 
         if r == "approved" and b == "approved":
@@ -702,7 +750,16 @@ class TestEntity:
             # Call self._events.append()
             self._events.append(DomainEvent("dual_validation_approved"))
 
-        elif r == "rejected" or b == "rejected":
-            # Any rejection is a veto — one lead can reject without waiting for the other
+        elif r == "rejected" and b == "rejected":
+            self.state = TestState.rejected
+            self._events.append(DomainEvent("dual_validation_rejected"))
+
+        elif (r == "approved" and b == "rejected") or (r == "rejected" and b == "approved"):
+            self.state = TestState.disputed
+            self._events.append(DomainEvent("dual_validation_disputed"))
+
+        elif r == "rejected" or b == "rejected":
+            # One side rejected while the other hasn't voted yet — no
+            # disagreement to dispute yet, just a straightforward veto.
             self.state = TestState.rejected
             self._events.append(DomainEvent("dual_validation_rejected"))
diff --git a/backend/app/routers/tests.py b/backend/app/routers/tests.py
index 7d2b930..4394df4 100644
--- a/backend/app/routers/tests.py
+++ b/backend/app/routers/tests.py
@@ -17,6 +17,7 @@ POST   /tests/{id}/submit-blue       — blue_evaluating → blue_review
 POST   /tests/{id}/review-blue       — assigned Blue Lead approves/reopens/flags gap
 POST   /tests/{id}/validate-red      — Red Lead validates
 POST   /tests/{id}/validate-blue     — Blue Lead validates
+POST   /tests/{id}/resolve-dispute   — approver flips to reject, routes to red/blue queue
 POST   /tests/{id}/reopen            — rejected → draft
 GET    /tests/{id}/timeline          — audit-log history for this test
 
@@ -69,6 +70,7 @@ from app.schemas.test import (
     TestRedUpdate,
     TestRedValidate,
     TestRemediationUpdate,
+    TestResolveDispute,
     TestUpdate,
 )
 
@@ -143,6 +145,7 @@ from app.services.test_workflow_service import (
     start_blue_work as wf_start_blue_work,
     validate_as_red_lead as wf_validate_red,
     validate_as_blue_lead as wf_validate_blue,
+    resolve_dispute as wf_resolve_dispute,
     reopen_test as wf_reopen,
     handle_remediation_completed as wf_handle_remediation,
     get_retest_chain as wf_get_retest_chain,
@@ -1158,6 +1161,27 @@ def validate_blue(
     return test
 
 
+# ---------------------------------------------------------------------------
+# POST /tests/{id}/resolve-dispute  —  approver flips to reject, picks a queue
+# ---------------------------------------------------------------------------
+
+
+@router.post("/{test_id}/resolve-dispute", response_model=TestOut)
+def resolve_dispute(
+    test_id: uuid.UUID,
+    payload: TestResolveDispute,
+    db: Session = Depends(get_db),
+    current_user: User = Depends(require_any_role("red_lead", "blue_lead", "admin")),
+) -> TestOut:
+    """The lead who approved flips their vote to reject, choosing which team must redo the work."""
+    test = crud_get_test_with_technique(db, test_id)
+    with UnitOfWork(db) as uow:
+        test = wf_resolve_dispute(db, test, current_user, payload.target_team, notes=payload.notes)
+        uow.commit()
+    db.refresh(test)
+    return test
+
+
 # ---------------------------------------------------------------------------
 # POST /tests/{id}/reopen  —  rejected → draft
 # ---------------------------------------------------------------------------
diff --git a/backend/app/schemas/test.py b/backend/app/schemas/test.py
index a7d3369..35d996e 100644
--- a/backend/app/schemas/test.py
+++ b/backend/app/schemas/test.py
@@ -125,6 +125,16 @@ class TestBlueValidate(BaseModel):
     blue_validation_notes: str | None = None
 
 
+# ── Dispute resolution ───────────────────────────────────────────────
+
+
+class TestResolveDispute(BaseModel):
+    """Payload sent by the approving lead flipping their vote to reject."""
+
+    target_team: str  # "red" | "blue" — which team must redo the work
+    notes: str | None = None
+
+
 # ── Red Lead review gate (pre-Blue-Team) ────────────────────────────
 
 
diff --git a/backend/app/services/test_workflow_service.py b/backend/app/services/test_workflow_service.py
index fad2f51..4027ff5 100644
--- a/backend/app/services/test_workflow_service.py
+++ b/backend/app/services/test_workflow_service.py
@@ -33,7 +33,11 @@ from app.models.evidence import Evidence
 from app.models.test import Test
 from app.models.user import User
 from app.services.audit_service import log_action
-from app.services.notification_service import notify_test_state_change, create_notification
+from app.services.notification_service import (
+    notify_test_state_change,
+    create_notification,
+    notify_role_with_email,
+)
 
 # Assign logger = logging.getLogger(__name__)
 logger = logging.getLogger(__name__)
@@ -1063,6 +1067,22 @@ def _dispatch_dual_validation_effects(
         elif event.name == "dual_validation_disputed":
             # Notify the lead who APPROVED asking them to review the rejection
             _notify_validation_conflict(db, test, actor)
+            # Notify managers too, in case the dispute stalls and needs escalation
+            try:
+                notify_role_with_email(
+                    db,
+                    role="manager",
+                    type="validation_disputed",
+                    title="Validation dispute needs oversight",
+                    message=(
+                        f'Test "{test.name}" has a validation dispute — one lead approved, '
+                        f'the other rejected. Escalate if it does not resolve.'
+                    ),
+                    entity_type="test",
+                    entity_id=test.id,
+                )
+            except Exception as e:
+                logger.warning("Manager dispute notification failed for test %s: %s", test.id, e, exc_info=True)
 
 
 def _notify_validation_conflict(db: Session, test: Test, actor: User | None) -> None:
@@ -1105,7 +1125,7 @@ def _notify_validation_conflict(db: Session, test: Test, actor: User | None) ->
                 f"or contact {rejector_role} to resolve the disagreement."
             ),
             entity_type="test",
-            entity_id=str(test.id),
+            entity_id=test.id,
         )
     except Exception as e:
         logger.warning(
@@ -1114,6 +1134,70 @@ def _notify_validation_conflict(db: Session, test: Test, actor: User | None) ->
         )
 
 
+def resolve_dispute(db: Session, test: Test, user: User, target_team: str, notes: str | None = None) -> Test:
+    """Resolve a disputed test by flipping the approving vote to reject.
+
+    Called by the lead who originally approved, now agreeing with the other
+    lead's rejection. Unlike a plain rejection, the flipping lead identifies
+    WHICH team's work needs redoing — the test routes straight back to that
+    team's active queue (red_executing or blue_evaluating) instead of the
+    generic 'rejected' state that would force a full draft restart for both
+    teams.
+    """
+    if target_team not in ("red", "blue"):
+        raise InvalidOperationError("target_team must be 'red' or 'blue'")
+
+    if user.role != "admin":
+        is_red_approver = user.role == "red_lead" and test.red_validation_status == "approved"
+        is_blue_approver = user.role == "blue_lead" and test.blue_validation_status == "approved"
+        if not (is_red_approver or is_blue_approver):
+            raise InvalidOperationError(
+                "Only the lead who approved can flip their vote to resolve this dispute"
+            )
+
+    entity = TestEntity.from_orm(test)
+    entity.resolve_dispute_reject(target_team)
+    entity.apply_to(test)
+
+    if target_team == "blue":
+        test.blue_work_started_at = None  # split responsibility: entity doesn't own this field
+
+    db.flush()
+
+    new_state = "red_executing" if target_team == "red" else "blue_evaluating"
+
+    log_action(
+        db, user_id=user.id, action="resolve_dispute",
+        entity_type="test", entity_id=test.id,
+        details={"target_team": target_team, "notes": notes, "test_name": test.name},
+    )
+
+    try:
+        notify_test_state_change(db, test, new_state)
+    except Exception as e:
+        logger.warning("Notification failed for test %s: %s", test.id, e, exc_info=True)
+
+    operator_id = test.red_tech_assignee if target_team == "red" else test.blue_tech_assignee
+    if operator_id and notes:
+        try:
+            create_notification(
+                db, user_id=operator_id, type="test_reopened",
+                title="Test sent back for rework (validation dispute)",
+                message=f'Test "{test.name}" needs rework: {notes[:200]}',
+                entity_type="test", entity_id=test.id,
+            )
+        except Exception as e:
+            logger.warning("Notification failed for test %s: %s", test.id, e, exc_info=True)
+
+    try:
+        from app.services.jira_service import push_test_event
+        push_test_event(db, test, user, new_state)
+    except Exception as e:
+        logger.warning("Jira push failed for test %s: %s", test.id, e, exc_info=True)
+
+    return test
+
+
 # Define function handle_remediation_completed
 def handle_remediation_completed(db: Session, test: Test, user: User) -> Test | None:
     """Create a re-test when remediation is completed.
diff --git a/backend/tests/test_resolve_dispute_router.py b/backend/tests/test_resolve_dispute_router.py
new file mode 100644
index 0000000..75119dd
--- /dev/null
+++ b/backend/tests/test_resolve_dispute_router.py
@@ -0,0 +1,114 @@
+"""HTTP-level tests for dispute resolution: POST /tests/{id}/resolve-dispute
+and the manager notification fired when a test enters 'disputed'.
+"""
+
+import uuid
+
+import pytest
+
+from app.models.evidence import Evidence
+from app.models.enums import TeamSide
+
+
+def _add_evidence(db, test_id, team: TeamSide):
+    ev = Evidence(
+        test_id=uuid.UUID(test_id),
+        file_name="proof.txt",
+        file_path="s3://bucket/proof.txt",
+        sha256_hash="a" * 64,
+        team=team,
+    )
+    db.add(ev)
+    db.commit()
+
+
+@pytest.fixture
+def technique(api, auth_headers):
+    resp = api(
+        "post", "/api/v1/techniques", auth_headers,
+        json={"mitre_id": "T1059.200", "name": "Command Line"},
+    )
+    assert resp.status_code == 201, resp.text
+    return resp.json()["id"]
+
+
+def _reach_disputed(client, db, api, auth_headers, red_tech_headers, red_lead_headers,
+                     blue_tech_headers, blue_lead_headers, technique):
+    """Drive a fresh test all the way to disputed: red approves, blue rejects."""
+    resp = api(
+        "post", "/api/v1/tests", auth_headers,
+        json={"technique_id": technique, "name": "Dispute test"},
+    )
+    test_id = resp.json()["id"]
+
+    api("post", f"/api/v1/tests/{test_id}/start-execution", red_tech_headers)
+    _add_evidence(db, test_id, TeamSide.red)
+    api("post", f"/api/v1/tests/{test_id}/submit-red", red_tech_headers)
+    api("post", f"/api/v1/tests/{test_id}/review-red", red_lead_headers, json={"decision": "approve"})
+
+    api("post", f"/api/v1/tests/{test_id}/start-blue-work", blue_tech_headers)
+    _add_evidence(db, test_id, TeamSide.blue)
+    api("post", f"/api/v1/tests/{test_id}/submit-blue", blue_tech_headers)
+    api("post", f"/api/v1/tests/{test_id}/review-blue", blue_lead_headers, json={"decision": "approve"})
+
+    red_vote = api(
+        "post", f"/api/v1/tests/{test_id}/validate-red", red_lead_headers,
+        json={"red_validation_status": "approved"},
+    )
+    assert red_vote.status_code == 200, red_vote.text
+
+    blue_vote = api(
+        "post", f"/api/v1/tests/{test_id}/validate-blue", blue_lead_headers,
+        json={"blue_validation_status": "rejected", "blue_validation_notes": "Detection insufficient"},
+    )
+    assert blue_vote.status_code == 200, blue_vote.text
+    assert blue_vote.json()["state"] == "disputed"
+
+    return test_id
+
+
+def test_manager_notified_on_dispute(
+    client, db, api, auth_headers, red_tech_headers, red_lead_headers,
+    blue_tech_headers, blue_lead_headers, manager_headers, manager_user, technique,
+):
+    _reach_disputed(client, db, api, auth_headers, red_tech_headers, red_lead_headers,
+                     blue_tech_headers, blue_lead_headers, technique)
+
+    resp = api("get", "/api/v1/notifications", manager_headers)
+    assert resp.status_code == 200
+    notifications = resp.json()
+    assert any(n["type"] == "validation_disputed" for n in notifications)
+
+
+def test_resolve_dispute_forbidden_for_non_approver(
+    client, db, api, auth_headers, red_tech_headers, red_lead_headers,
+    blue_tech_headers, blue_lead_headers, technique,
+):
+    """Blue Lead rejected (didn't approve) — they cannot flip the vote here."""
+    test_id = _reach_disputed(client, db, api, auth_headers, red_tech_headers, red_lead_headers,
+                               blue_tech_headers, blue_lead_headers, technique)
+
+    resp = api(
+        "post", f"/api/v1/tests/{test_id}/resolve-dispute", blue_lead_headers,
+        json={"target_team": "blue"},
+    )
+    assert resp.status_code == 400
+
+
+def test_resolve_dispute_routes_to_red_queue(
+    client, db, api, auth_headers, red_tech_headers, red_lead_headers,
+    blue_tech_headers, blue_lead_headers, technique,
+):
+    """Red Lead approved; flips to reject and sends it to the Red queue."""
+    test_id = _reach_disputed(client, db, api, auth_headers, red_tech_headers, red_lead_headers,
+                               blue_tech_headers, blue_lead_headers, technique)
+
+    resp = api(
+        "post", f"/api/v1/tests/{test_id}/resolve-dispute", red_lead_headers,
+        json={"target_team": "red", "notes": "redo the attack with more detail"},
+    )
+    assert resp.status_code == 200, resp.text
+    body = resp.json()
+    assert body["state"] == "red_executing"
+    assert body["red_validation_status"] is None
+    assert body["blue_validation_status"] is None
diff --git a/backend/tests/test_test_entity.py b/backend/tests/test_test_entity.py
index 8afe59c..4226a3b 100644
--- a/backend/tests/test_test_entity.py
+++ b/backend/tests/test_test_entity.py
@@ -401,9 +401,32 @@ def test_dual_validation_red_rejects():
 
 
 def test_dual_validation_blue_rejects():
+    """Red already approved; Blue then rejects — a genuine conflict, not a veto."""
     e = _entity("in_review")
     e.validate_red("approved", by=uuid.uuid4())
     e.validate_blue("rejected", by=uuid.uuid4())
+    assert e.state == TestState.disputed
+    assert any(ev.name == "dual_validation_disputed" for ev in e.events)
+
+
+def test_dual_validation_blue_approved_then_red_rejects():
+    """Blue already approved; Red then rejects — also a genuine conflict."""
+    e = _entity("in_review")
+    e.validate_blue("approved", by=uuid.uuid4())
+    e.validate_red("rejected", by=uuid.uuid4())
+    assert e.state == TestState.disputed
+
+
+def test_dual_validation_both_rejected_from_disputed():
+    """A disputed test where the approving lead flips to reject (via the
+    plain validate call, not resolve_dispute_reject) still lands on the
+    generic terminal 'rejected' state — both leads now agree it's bad."""
+    e = _entity(
+        "disputed",
+        red_validation_status="approved",
+        blue_validation_status="rejected",
+    )
+    e.validate_red("rejected", by=uuid.uuid4())
     assert e.state == TestState.rejected
 
 
@@ -561,3 +584,52 @@ def test_is_terminal():
     assert _entity("validated").is_terminal is True
     assert _entity("rejected").is_terminal is False
     assert _entity("draft").is_terminal is False
+
+
+# ── 13. resolve_dispute_reject ──────────────────────────────────────
+
+
+def test_resolve_dispute_reject_to_red():
+    e = _entity(
+        "disputed",
+        red_validation_status="approved",
+        red_validated_by=uuid.uuid4(),
+        red_validated_at=datetime.utcnow(),
+        blue_validation_status="rejected",
+        blue_validated_by=uuid.uuid4(),
+        blue_validated_at=datetime.utcnow(),
+        red_paused_seconds=50,
+    )
+    e.resolve_dispute_reject("red")
+    assert e.state == TestState.red_executing
+    assert e.red_validation_status is None
+    assert e.red_validated_by is None
+    assert e.blue_validation_status is None
+    assert e.blue_validated_by is None
+    assert e.red_started_at is not None
+    assert e.red_paused_seconds == 0
+    assert any(ev.name == "dispute_resolved_to_rework" and ev.payload["target"] == "red" for ev in e.events)
+
+
+def test_resolve_dispute_reject_to_blue():
+    e = _entity(
+        "disputed",
+        blue_validation_status="approved",
+        blue_validated_by=uuid.uuid4(),
+        red_validation_status="rejected",
+        red_validated_by=uuid.uuid4(),
+        blue_paused_seconds=20,
+    )
+    e.resolve_dispute_reject("blue")
+    assert e.state == TestState.blue_evaluating
+    assert e.red_validation_status is None
+    assert e.blue_validation_status is None
+    assert e.blue_started_at is not None
+    assert e.blue_paused_seconds == 0
+    assert any(ev.name == "dispute_resolved_to_rework" and ev.payload["target"] == "blue" for ev in e.events)
+
+
+def test_resolve_dispute_reject_wrong_state():
+    e = _entity("in_review")
+    with pytest.raises(InvalidStateTransition):
+        e.resolve_dispute_reject("red")
diff --git a/backend/tests/test_workflow.py b/backend/tests/test_workflow.py
index de511b1..ac46b65 100644
--- a/backend/tests/test_workflow.py
+++ b/backend/tests/test_workflow.py
@@ -414,7 +414,7 @@ def test_dual_validation_blue_rejects_first(mock_log):
 
 @patch("app.services.test_workflow_service.log_action")
 def test_dual_validation_red_approves_blue_rejects(mock_log):
-    """Red approves, then blue rejects -> rejected."""
+    """Red approves, then blue rejects -> genuine conflict -> disputed."""
     test = _make_test(TestState.in_review)
     red_lead = _make_user("red_lead")
     blue_lead = _make_user("blue_lead")
@@ -424,7 +424,7 @@ def test_dual_validation_red_approves_blue_rejects(mock_log):
     assert test.state == TestState.in_review  # waiting for blue
 
     validate_as_blue_lead(db, test, blue_lead, "rejected", "Bad detection")
-    assert test.state == TestState.rejected
+    assert test.state == TestState.disputed
 
 
 # ===========================================================================
@@ -687,6 +687,85 @@ class TestReviewDecisions:
         assert result.system_gaps == "Missing EDR agent on host X"
 
 
+# ===========================================================================
+# 12c. resolve_dispute — flip approver's vote to reject, route to a team
+# ===========================================================================
+
+
+class TestResolveDispute:
+    @patch("app.services.test_workflow_service.log_action")
+    def test_red_lead_approver_flips_to_red_queue(self, mock_log):
+        test = _make_test(
+            TestState.disputed,
+            red_validation_status="approved",
+            blue_validation_status="rejected",
+        )
+        red_lead = _make_user("red_lead")
+        db = _make_db()
+
+        from app.services.test_workflow_service import resolve_dispute
+        result = resolve_dispute(db, test, red_lead, "red", notes="redo the attack")
+
+        assert result.state == TestState.red_executing
+        assert result.red_validation_status is None
+        assert result.blue_validation_status is None
+
+    @patch("app.services.test_workflow_service.log_action")
+    def test_blue_lead_approver_flips_to_blue_queue(self, mock_log):
+        test = _make_test(
+            TestState.disputed,
+            blue_validation_status="approved",
+            red_validation_status="rejected",
+        )
+        blue_lead = _make_user("blue_lead")
+        db = _make_db()
+
+        from app.services.test_workflow_service import resolve_dispute
+        result = resolve_dispute(db, test, blue_lead, "blue")
+
+        assert result.state == TestState.blue_evaluating
+
+    def test_non_approver_cannot_resolve_dispute(self):
+        test = _make_test(
+            TestState.disputed,
+            red_validation_status="rejected",
+            blue_validation_status="approved",
+        )
+        red_lead = _make_user("red_lead")  # red_lead REJECTED, didn't approve
+        db = _make_db()
+
+        from app.services.test_workflow_service import resolve_dispute
+        with pytest.raises(InvalidOperationError):
+            resolve_dispute(db, test, red_lead, "red")
+
+    def test_invalid_target_team_rejected(self):
+        test = _make_test(
+            TestState.disputed,
+            red_validation_status="approved",
+            blue_validation_status="rejected",
+        )
+        red_lead = _make_user("red_lead")
+        db = _make_db()
+
+        from app.services.test_workflow_service import resolve_dispute
+        with pytest.raises(InvalidOperationError):
+            resolve_dispute(db, test, red_lead, "purple")
+
+    @patch("app.services.test_workflow_service.log_action")
+    def test_admin_can_resolve_dispute_regardless_of_vote(self, mock_log):
+        test = _make_test(
+            TestState.disputed,
+            red_validation_status="approved",
+            blue_validation_status="rejected",
+        )
+        admin = _make_user("admin")
+        db = _make_db()
+
+        from app.services.test_workflow_service import resolve_dispute
+        result = resolve_dispute(db, test, admin, "red")
+        assert result.state == TestState.red_executing
+
+
 # ===========================================================================
 # 13. select_reviewer — load-balanced reviewer assignment
 # ===========================================================================