diff --git a/services/graph/app/fsma_recall/models.py b/services/graph/app/fsma_recall/models.py
index 88e380279..ee43c8fcd 100644
--- a/services/graph/app/fsma_recall/models.py
+++ b/services/graph/app/fsma_recall/models.py
@@ -122,8 +122,11 @@ def sla_status(self) -> SLAStatus:
         if self.status == RecallStatus.COMPLETED:
             duration = self.duration_seconds
             # 0 seconds is a valid (instant) completion, so compare against
-            # None rather than relying on truthiness.
-            if duration is not None and duration <= sla_limit:
+            # None rather than relying on truthiness. A negative duration
+            # (completed_at before started_at) is corrupt timing data; it must
+            # never certify compliance, so fail closed as BREACHED rather than
+            # introducing a new status value API consumers don't expect.
+            if duration is not None and 0 <= duration <= sla_limit:
                 return SLAStatus.MET
             return SLAStatus.BREACHED
 
diff --git a/services/graph/tests/test_recall_sla_negative_duration.py b/services/graph/tests/test_recall_sla_negative_duration.py
new file mode 100644
index 000000000..07c053fcb
--- /dev/null
+++ b/services/graph/tests/test_recall_sla_negative_duration.py
@@ -0,0 +1,48 @@
+"""Data-free tests: a completed drill with completed_at before started_at.
+
+A negative duration is corrupt timing data and must never certify 24-hour
+compliance (21 CFR 1.1455(c)(1)). It fails closed as BREACHED, the existing
+non-compliant status, rather than a new enum value.
+Timestamps only; no records, CSV rows or EPCIS documents.
+"""
+
+from __future__ import annotations
+
+from datetime import datetime, timedelta, timezone
+
+from services.graph.app.fsma_recall.models import (
+    RecallDrill,
+    RecallSeverity,
+    RecallStatus,
+    RecallType,
+    SLAStatus,
+)
+
+START = datetime(2026, 1, 1, tzinfo=timezone.utc)
+
+
+def _completed(elapsed: timedelta) -> RecallDrill:
+    return RecallDrill(
+        drill_id="",
+        tenant_id="",
+        created_at=START,
+        drill_type=list(RecallType)[0],
+        severity=list(RecallSeverity)[0],
+        status=RecallStatus.COMPLETED,
+        started_at=START,
+        completed_at=START + elapsed,
+    )
+
+
+def test_negative_duration_is_not_met():
+    drill = _completed(timedelta(seconds=-1))
+    assert drill.duration_seconds == -1
+    assert drill.sla_status == SLAStatus.BREACHED
+
+
+def test_large_negative_duration_is_breached():
+    assert _completed(timedelta(hours=-48)).sla_status == SLAStatus.BREACHED
+
+
+def test_zero_still_met():
+    assert _completed(timedelta(0)).sla_status == SLAStatus.MET