diff --git a/.sdkharness/tests/conformance/lock.bypass_governance b/.sdkharness/tests/conformance/lock.bypass_governance
index 257777a9..570f778b 100755
--- a/.sdkharness/tests/conformance/lock.bypass_governance
+++ b/.sdkharness/tests/conformance/lock.bypass_governance
@@ -18,6 +18,16 @@ delete is refused: 401 access_denied, "The delete was not allowed because
 Object Lock is enabled on the file."
 https://www.backblaze.com/apidocs/b2-delete-file-version
 
+401 access_denied is accepted as the refusal. B2's raw-API contract test for this
+exact call (test/integration/test_raw_api.py: `with pytest.raises(Unauthorized):
+raw_api.delete_file_version(...)` on a governance-locked version, then the
+bypassing delete succeeds) passes against real B2 with a 401, and b2sdk raises
+Unauthorized (code access_denied) for it; the simulator's default profile answers
+the same. A refusal for an unrelated reason is still a failure: an
+InvalidAuthToken (bad or expired token), any other Unauthorized code, a 5xx or a
+network error does not count. The exact error code and message are not verified
+against real B2 (UNVERIFIED in the simulator ledger, docs/FIDELITY.md).
+
 Written from bin/conformance/b2-sdk-python/files.upload, the reference check,
 and bin/conformance/README.md, the contract. It exercises b2sdk from this exact repository
 checkout; the API was taken from
@@ -119,11 +129,15 @@ def step(name, action):
         raise Failure(name, name_of) from error
 
 
-def refused(name, action, expected):
+def refused(name, action, expected, *, access_denied_401=False):
     """Assert something is REFUSED, and record what refused it.
 
     `expected` is a tuple of exception class names. A different class -- or no
     exception at all -- is a Failure, because the refusal IS the claim here.
+    With `access_denied_401`, b2sdk's Unauthorized is also accepted, but only
+    when its code is `access_denied` (a 401 about Object Lock, as B2 answers a
+    delete without bypassGovernance); InvalidAuthToken and every other
+    Unauthorized code stay failures.
     """
     try:
         action()
@@ -133,6 +147,12 @@ def refused(name, action, expected):
         name_of = type(error).__name__
         if name_of in expected:
             return name_of
+        if (
+            access_denied_401
+            and name_of == 'Unauthorized'
+            and getattr(error, 'code', None) == 'access_denied'
+        ):
+            return 'Unauthorized(access_denied)'
         raise Failure(name, f"refused with {name_of}, expected {'/'.join(expected)}") from error
     raise Failure(name, 'the call was permitted; the claim under test is that it is refused')
 
@@ -269,6 +289,7 @@ def run(target: str) -> None:
             'delete without bypass',
             lambda: bucket.delete_file_version(uploaded.id_, OBJECT_NAME),
             ('AccessDenied', 'RetentionWriteError', 'Conflict', 'BadRequest'),
+            access_denied_401=True,
         )
 
         step(
diff --git a/.sdkharness/tests/conformance/lock.per_file_retention b/.sdkharness/tests/conformance/lock.per_file_retention
index d310bbd6..93f28b82 100755
--- a/.sdkharness/tests/conformance/lock.per_file_retention
+++ b/.sdkharness/tests/conformance/lock.per_file_retention
@@ -20,6 +20,16 @@ and bypassGovernance "Must be specified and set to true if deleting a file
 version protected by Object Lock governance mode retention settings."
 https://www.backblaze.com/apidocs/b2-delete-file-version
 
+401 access_denied is accepted as the refusal. B2's raw-API contract test for this
+exact call (test/integration/test_raw_api.py: `with pytest.raises(Unauthorized):
+raw_api.delete_file_version(...)` on a governance-locked version, then the
+bypassing delete succeeds) passes against real B2 with a 401, and b2sdk raises
+Unauthorized (code access_denied) for it; the simulator's default profile answers
+the same. A refusal for an unrelated reason is still a failure: an
+InvalidAuthToken (bad or expired token), any other Unauthorized code, a 5xx or a
+network error does not count. The exact error code and message are not verified
+against real B2 (UNVERIFIED in the simulator ledger, docs/FIDELITY.md).
+
 Written from bin/conformance/b2-sdk-python/files.upload, the reference check,
 and bin/conformance/README.md, the contract. It exercises b2sdk from this exact repository
 checkout; the API was taken from
@@ -121,11 +131,15 @@ def step(name, action):
         raise Failure(name, name_of) from error
 
 
-def refused(name, action, expected):
+def refused(name, action, expected, *, access_denied_401=False):
     """Assert something is REFUSED, and record what refused it.
 
     `expected` is a tuple of exception class names. A different class -- or no
     exception at all -- is a Failure, because the refusal IS the claim here.
+    With `access_denied_401`, b2sdk's Unauthorized is also accepted, but only
+    when its code is `access_denied` (a 401 about Object Lock, as B2 answers a
+    delete without bypassGovernance); InvalidAuthToken and every other
+    Unauthorized code stay failures.
     """
     try:
         action()
@@ -135,6 +149,12 @@ def refused(name, action, expected):
         name_of = type(error).__name__
         if name_of in expected:
             return name_of
+        if (
+            access_denied_401
+            and name_of == 'Unauthorized'
+            and getattr(error, 'code', None) == 'access_denied'
+        ):
+            return 'Unauthorized(access_denied)'
         raise Failure(name, f"refused with {name_of}, expected {'/'.join(expected)}") from error
     raise Failure(name, 'the call was permitted; the claim under test is that it is refused')
 
@@ -278,6 +298,7 @@ def run(target: str) -> None:
             'delete without bypass',
             lambda: bucket.delete_file_version(uploaded.id_, OBJECT_NAME),
             ('AccessDenied', 'RetentionWriteError', 'Conflict', 'BadRequest'),
+            access_denied_401=True,
         )
     finally:
         teardown(api, bucket)
diff --git a/changelog.d/+sdkharness-lock-refusal.infrastructure.md b/changelog.d/+sdkharness-lock-refusal.infrastructure.md
new file mode 100644
index 00000000..b30c9f91
--- /dev/null
+++ b/changelog.d/+sdkharness-lock-refusal.infrastructure.md
@@ -0,0 +1 @@
+Repository-owned conformance checks `lock.bypass_governance` and `lock.per_file_retention` accept the 401 `access_denied` that B2 answers for a delete of a governance-locked version without bypass, and still fail if the delete is allowed or refused for an unrelated reason.
diff --git a/test/unit/test_sdkharness_lock_refusal.py b/test/unit/test_sdkharness_lock_refusal.py
new file mode 100644
index 00000000..5c6ebf45
--- /dev/null
+++ b/test/unit/test_sdkharness_lock_refusal.py
@@ -0,0 +1,113 @@
+######################################################################
+#
+# File: test/unit/test_sdkharness_lock_refusal.py
+#
+# Copyright 2026 Backblaze Inc. All Rights Reserved.
+#
+# License https://www.backblaze.com/using_b2_code.html
+#
+######################################################################
+from __future__ import annotations
+
+from importlib.machinery import SourceFileLoader
+from importlib.util import module_from_spec, spec_from_loader
+from pathlib import Path
+
+import pytest
+
+CONFORMANCE = Path(__file__).parents[2] / '.sdkharness' / 'tests' / 'conformance'
+LEAVES = ('lock.bypass_governance', 'lock.per_file_retention')
+EXPECTED = ('AccessDenied', 'RetentionWriteError', 'Conflict', 'BadRequest')
+
+
+def load_leaf(name):
+    loader = SourceFileLoader(f'sdkharness_leaf_{name.replace(".", "_")}', str(CONFORMANCE / name))
+    spec = spec_from_loader(loader.name, loader)
+    module = module_from_spec(spec)
+    loader.exec_module(module)
+    return module
+
+
+# `refused` classifies by class name, as the leaves do, so these stand-ins carry
+# b2sdk's names. Unauthorized carries the `code` b2sdk reads from the response.
+class Unauthorized(Exception):
+    def __init__(self, code):
+        super().__init__(code)
+        self.code = code
+
+
+class InvalidAuthToken(Unauthorized):
+    pass
+
+
+class ServiceError(Exception):
+    pass
+
+
+def raising(error):
+    def action():
+        raise error
+
+    return action
+
+
+@pytest.mark.parametrize('leaf', LEAVES)
+def test_401_access_denied_counts_as_the_refusal(leaf):
+    module = load_leaf(leaf)
+    got = module.refused(
+        'delete without bypass',
+        raising(Unauthorized('access_denied')),
+        EXPECTED,
+        access_denied_401=True,
+    )
+    assert got == 'Unauthorized(access_denied)'
+
+
+@pytest.mark.parametrize('leaf', LEAVES)
+def test_the_old_refusal_classes_are_still_accepted(leaf):
+    module = load_leaf(leaf)
+    AccessDenied = type('AccessDenied', (Exception,), {})
+    assert (
+        module.refused(
+            'delete without bypass', raising(AccessDenied()), EXPECTED, access_denied_401=True
+        )
+        == 'AccessDenied'
+    )
+
+
+@pytest.mark.parametrize('leaf', LEAVES)
+def test_an_allowed_operation_still_fails(leaf):
+    module = load_leaf(leaf)
+    with pytest.raises(module.Failure, match='permitted'):
+        module.refused('delete without bypass', lambda: None, EXPECTED, access_denied_401=True)
+
+
+@pytest.mark.parametrize('leaf', LEAVES)
+@pytest.mark.parametrize(
+    'error',
+    [
+        InvalidAuthToken('expired_auth_token'),
+        Unauthorized('bad_auth_token'),
+        Unauthorized('email_not_verified'),
+        ServiceError('503'),
+        KeyError('404'),
+    ],
+    ids=['bad-token', 'other-401-code', 'unverified-email', '5xx', 'not-found'],
+)
+def test_an_unrelated_refusal_still_fails(leaf, error):
+    module = load_leaf(leaf)
+    with pytest.raises(module.Failure, match='refused with'):
+        module.refused('delete without bypass', raising(error), EXPECTED, access_denied_401=True)
+
+
+@pytest.mark.parametrize('leaf', LEAVES)
+def test_unauthorized_is_not_accepted_unless_asked(leaf):
+    module = load_leaf(leaf)
+    with pytest.raises(module.Failure):
+        module.refused('delete without bypass', raising(Unauthorized('access_denied')), EXPECTED)
+
+
+@pytest.mark.parametrize('leaf', LEAVES)
+def test_the_leaf_asks_for_the_401_on_its_delete_without_bypass(leaf):
+    source = (CONFORMANCE / leaf).read_text()
+    assert 'access_denied_401=True' in source