diff --git a/google/cloud/workflows/executions_v1/services/executions/transports/base.py b/google/cloud/workflows/executions_v1/services/executions/transports/base.py
index 363e292..a209877 100644
--- a/google/cloud/workflows/executions_v1/services/executions/transports/base.py
+++ b/google/cloud/workflows/executions_v1/services/executions/transports/base.py
@@ -96,7 +96,7 @@ def __init__(
         scopes_kwargs = self._get_scopes_kwargs(self._host, scopes)
 
         # Save the scopes.
-        self._scopes = scopes or self.AUTH_SCOPES
+        self._scopes = scopes
 
         # If no credentials are provided, then determine the appropriate
         # defaults.
diff --git a/google/cloud/workflows/executions_v1/services/executions/transports/grpc.py b/google/cloud/workflows/executions_v1/services/executions/transports/grpc.py
index 617f273..1e3a06e 100644
--- a/google/cloud/workflows/executions_v1/services/executions/transports/grpc.py
+++ b/google/cloud/workflows/executions_v1/services/executions/transports/grpc.py
@@ -58,6 +58,7 @@ def __init__(
         client_cert_source_for_mtls: Callable[[], Tuple[bytes, bytes]] = None,
         quota_project_id: Optional[str] = None,
         client_info: gapic_v1.client_info.ClientInfo = DEFAULT_CLIENT_INFO,
+        always_use_jwt_access: Optional[bool] = False,
     ) -> None:
         """Instantiate the transport.
 
@@ -98,6 +99,8 @@ def __init__(
                 API requests. If ``None``, then default info will be used.
                 Generally, you only need to set this if you're developing
                 your own client library.
+            always_use_jwt_access (Optional[bool]): Whether self signed JWT should
+                be used for service account credentials.
 
         Raises:
           google.auth.exceptions.MutualTLSChannelError: If mutual TLS transport
@@ -150,7 +153,7 @@ def __init__(
             scopes=scopes,
             quota_project_id=quota_project_id,
             client_info=client_info,
-            always_use_jwt_access=True,
+            always_use_jwt_access=always_use_jwt_access,
         )
 
         if not self._grpc_channel:
diff --git a/google/cloud/workflows/executions_v1/services/executions/transports/grpc_asyncio.py b/google/cloud/workflows/executions_v1/services/executions/transports/grpc_asyncio.py
index dfa2644..1992e43 100644
--- a/google/cloud/workflows/executions_v1/services/executions/transports/grpc_asyncio.py
+++ b/google/cloud/workflows/executions_v1/services/executions/transports/grpc_asyncio.py
@@ -104,6 +104,7 @@ def __init__(
         client_cert_source_for_mtls: Callable[[], Tuple[bytes, bytes]] = None,
         quota_project_id=None,
         client_info: gapic_v1.client_info.ClientInfo = DEFAULT_CLIENT_INFO,
+        always_use_jwt_access: Optional[bool] = False,
     ) -> None:
         """Instantiate the transport.
 
@@ -145,6 +146,8 @@ def __init__(
                 API requests. If ``None``, then default info will be used.
                 Generally, you only need to set this if you're developing
                 your own client library.
+            always_use_jwt_access (Optional[bool]): Whether self signed JWT should
+                be used for service account credentials.
 
         Raises:
             google.auth.exceptions.MutualTlsChannelError: If mutual TLS transport
@@ -196,7 +199,7 @@ def __init__(
             scopes=scopes,
             quota_project_id=quota_project_id,
             client_info=client_info,
-            always_use_jwt_access=True,
+            always_use_jwt_access=always_use_jwt_access,
         )
 
         if not self._grpc_channel:
diff --git a/google/cloud/workflows/executions_v1beta/services/executions/transports/base.py b/google/cloud/workflows/executions_v1beta/services/executions/transports/base.py
index 25223ec..9b02612 100644
--- a/google/cloud/workflows/executions_v1beta/services/executions/transports/base.py
+++ b/google/cloud/workflows/executions_v1beta/services/executions/transports/base.py
@@ -96,7 +96,7 @@ def __init__(
         scopes_kwargs = self._get_scopes_kwargs(self._host, scopes)
 
         # Save the scopes.
-        self._scopes = scopes or self.AUTH_SCOPES
+        self._scopes = scopes
 
         # If no credentials are provided, then determine the appropriate
         # defaults.
diff --git a/google/cloud/workflows/executions_v1beta/services/executions/transports/grpc.py b/google/cloud/workflows/executions_v1beta/services/executions/transports/grpc.py
index 082b6af..ec95e1b 100644
--- a/google/cloud/workflows/executions_v1beta/services/executions/transports/grpc.py
+++ b/google/cloud/workflows/executions_v1beta/services/executions/transports/grpc.py
@@ -59,6 +59,7 @@ def __init__(
         client_cert_source_for_mtls: Callable[[], Tuple[bytes, bytes]] = None,
         quota_project_id: Optional[str] = None,
         client_info: gapic_v1.client_info.ClientInfo = DEFAULT_CLIENT_INFO,
+        always_use_jwt_access: Optional[bool] = False,
     ) -> None:
         """Instantiate the transport.
 
@@ -99,6 +100,8 @@ def __init__(
                 API requests. If ``None``, then default info will be used.
                 Generally, you only need to set this if you're developing
                 your own client library.
+            always_use_jwt_access (Optional[bool]): Whether self signed JWT should
+                be used for service account credentials.
 
         Raises:
           google.auth.exceptions.MutualTLSChannelError: If mutual TLS transport
@@ -151,7 +154,7 @@ def __init__(
             scopes=scopes,
             quota_project_id=quota_project_id,
             client_info=client_info,
-            always_use_jwt_access=True,
+            always_use_jwt_access=always_use_jwt_access,
         )
 
         if not self._grpc_channel:
diff --git a/google/cloud/workflows/executions_v1beta/services/executions/transports/grpc_asyncio.py b/google/cloud/workflows/executions_v1beta/services/executions/transports/grpc_asyncio.py
index 61f55b0..e28c529 100644
--- a/google/cloud/workflows/executions_v1beta/services/executions/transports/grpc_asyncio.py
+++ b/google/cloud/workflows/executions_v1beta/services/executions/transports/grpc_asyncio.py
@@ -105,6 +105,7 @@ def __init__(
         client_cert_source_for_mtls: Callable[[], Tuple[bytes, bytes]] = None,
         quota_project_id=None,
         client_info: gapic_v1.client_info.ClientInfo = DEFAULT_CLIENT_INFO,
+        always_use_jwt_access: Optional[bool] = False,
     ) -> None:
         """Instantiate the transport.
 
@@ -146,6 +147,8 @@ def __init__(
                 API requests. If ``None``, then default info will be used.
                 Generally, you only need to set this if you're developing
                 your own client library.
+            always_use_jwt_access (Optional[bool]): Whether self signed JWT should
+                be used for service account credentials.
 
         Raises:
             google.auth.exceptions.MutualTlsChannelError: If mutual TLS transport
@@ -197,7 +200,7 @@ def __init__(
             scopes=scopes,
             quota_project_id=quota_project_id,
             client_info=client_info,
-            always_use_jwt_access=True,
+            always_use_jwt_access=always_use_jwt_access,
         )
 
         if not self._grpc_channel:
diff --git a/google/cloud/workflows_v1/services/workflows/transports/base.py b/google/cloud/workflows_v1/services/workflows/transports/base.py
index e39dc06..05ec31f 100644
--- a/google/cloud/workflows_v1/services/workflows/transports/base.py
+++ b/google/cloud/workflows_v1/services/workflows/transports/base.py
@@ -98,7 +98,7 @@ def __init__(
         scopes_kwargs = self._get_scopes_kwargs(self._host, scopes)
 
         # Save the scopes.
-        self._scopes = scopes or self.AUTH_SCOPES
+        self._scopes = scopes
 
         # If no credentials are provided, then determine the appropriate
         # defaults.
diff --git a/google/cloud/workflows_v1/services/workflows/transports/grpc.py b/google/cloud/workflows_v1/services/workflows/transports/grpc.py
index b303461..439055a 100644
--- a/google/cloud/workflows_v1/services/workflows/transports/grpc.py
+++ b/google/cloud/workflows_v1/services/workflows/transports/grpc.py
@@ -61,6 +61,7 @@ def __init__(
         client_cert_source_for_mtls: Callable[[], Tuple[bytes, bytes]] = None,
         quota_project_id: Optional[str] = None,
         client_info: gapic_v1.client_info.ClientInfo = DEFAULT_CLIENT_INFO,
+        always_use_jwt_access: Optional[bool] = False,
     ) -> None:
         """Instantiate the transport.
 
@@ -101,6 +102,8 @@ def __init__(
                 API requests. If ``None``, then default info will be used.
                 Generally, you only need to set this if you're developing
                 your own client library.
+            always_use_jwt_access (Optional[bool]): Whether self signed JWT should
+                be used for service account credentials.
 
         Raises:
           google.auth.exceptions.MutualTLSChannelError: If mutual TLS transport
@@ -154,7 +157,7 @@ def __init__(
             scopes=scopes,
             quota_project_id=quota_project_id,
             client_info=client_info,
-            always_use_jwt_access=True,
+            always_use_jwt_access=always_use_jwt_access,
         )
 
         if not self._grpc_channel:
diff --git a/google/cloud/workflows_v1/services/workflows/transports/grpc_asyncio.py b/google/cloud/workflows_v1/services/workflows/transports/grpc_asyncio.py
index 6318fb3..d8c532d 100644
--- a/google/cloud/workflows_v1/services/workflows/transports/grpc_asyncio.py
+++ b/google/cloud/workflows_v1/services/workflows/transports/grpc_asyncio.py
@@ -107,6 +107,7 @@ def __init__(
         client_cert_source_for_mtls: Callable[[], Tuple[bytes, bytes]] = None,
         quota_project_id=None,
         client_info: gapic_v1.client_info.ClientInfo = DEFAULT_CLIENT_INFO,
+        always_use_jwt_access: Optional[bool] = False,
     ) -> None:
         """Instantiate the transport.
 
@@ -148,6 +149,8 @@ def __init__(
                 API requests. If ``None``, then default info will be used.
                 Generally, you only need to set this if you're developing
                 your own client library.
+            always_use_jwt_access (Optional[bool]): Whether self signed JWT should
+                be used for service account credentials.
 
         Raises:
             google.auth.exceptions.MutualTlsChannelError: If mutual TLS transport
@@ -200,7 +203,7 @@ def __init__(
             scopes=scopes,
             quota_project_id=quota_project_id,
             client_info=client_info,
-            always_use_jwt_access=True,
+            always_use_jwt_access=always_use_jwt_access,
         )
 
         if not self._grpc_channel:
diff --git a/google/cloud/workflows_v1beta/services/workflows/transports/base.py b/google/cloud/workflows_v1beta/services/workflows/transports/base.py
index e2b419c..bb171c3 100644
--- a/google/cloud/workflows_v1beta/services/workflows/transports/base.py
+++ b/google/cloud/workflows_v1beta/services/workflows/transports/base.py
@@ -98,7 +98,7 @@ def __init__(
         scopes_kwargs = self._get_scopes_kwargs(self._host, scopes)
 
         # Save the scopes.
-        self._scopes = scopes or self.AUTH_SCOPES
+        self._scopes = scopes
 
         # If no credentials are provided, then determine the appropriate
         # defaults.
diff --git a/google/cloud/workflows_v1beta/services/workflows/transports/grpc.py b/google/cloud/workflows_v1beta/services/workflows/transports/grpc.py
index 1e41a71..d4897e9 100644
--- a/google/cloud/workflows_v1beta/services/workflows/transports/grpc.py
+++ b/google/cloud/workflows_v1beta/services/workflows/transports/grpc.py
@@ -61,6 +61,7 @@ def __init__(
         client_cert_source_for_mtls: Callable[[], Tuple[bytes, bytes]] = None,
         quota_project_id: Optional[str] = None,
         client_info: gapic_v1.client_info.ClientInfo = DEFAULT_CLIENT_INFO,
+        always_use_jwt_access: Optional[bool] = False,
     ) -> None:
         """Instantiate the transport.
 
@@ -101,6 +102,8 @@ def __init__(
                 API requests. If ``None``, then default info will be used.
                 Generally, you only need to set this if you're developing
                 your own client library.
+            always_use_jwt_access (Optional[bool]): Whether self signed JWT should
+                be used for service account credentials.
 
         Raises:
           google.auth.exceptions.MutualTLSChannelError: If mutual TLS transport
@@ -154,7 +157,7 @@ def __init__(
             scopes=scopes,
             quota_project_id=quota_project_id,
             client_info=client_info,
-            always_use_jwt_access=True,
+            always_use_jwt_access=always_use_jwt_access,
         )
 
         if not self._grpc_channel:
diff --git a/google/cloud/workflows_v1beta/services/workflows/transports/grpc_asyncio.py b/google/cloud/workflows_v1beta/services/workflows/transports/grpc_asyncio.py
index 3a6452d..92b21d7 100644
--- a/google/cloud/workflows_v1beta/services/workflows/transports/grpc_asyncio.py
+++ b/google/cloud/workflows_v1beta/services/workflows/transports/grpc_asyncio.py
@@ -107,6 +107,7 @@ def __init__(
         client_cert_source_for_mtls: Callable[[], Tuple[bytes, bytes]] = None,
         quota_project_id=None,
         client_info: gapic_v1.client_info.ClientInfo = DEFAULT_CLIENT_INFO,
+        always_use_jwt_access: Optional[bool] = False,
     ) -> None:
         """Instantiate the transport.
 
@@ -148,6 +149,8 @@ def __init__(
                 API requests. If ``None``, then default info will be used.
                 Generally, you only need to set this if you're developing
                 your own client library.
+            always_use_jwt_access (Optional[bool]): Whether self signed JWT should
+                be used for service account credentials.
 
         Raises:
             google.auth.exceptions.MutualTlsChannelError: If mutual TLS transport
@@ -200,7 +203,7 @@ def __init__(
             scopes=scopes,
             quota_project_id=quota_project_id,
             client_info=client_info,
-            always_use_jwt_access=True,
+            always_use_jwt_access=always_use_jwt_access,
         )
 
         if not self._grpc_channel:
diff --git a/tests/unit/gapic/executions_v1/test_executions.py b/tests/unit/gapic/executions_v1/test_executions.py
index 780a99c..acc1ebf 100644
--- a/tests/unit/gapic/executions_v1/test_executions.py
+++ b/tests/unit/gapic/executions_v1/test_executions.py
@@ -123,7 +123,25 @@ def test_executions_client_service_account_always_use_jwt(client_class):
     ) as use_jwt:
         creds = service_account.Credentials(None, None, None)
         client = client_class(credentials=creds)
-        use_jwt.assert_called_with(True)
+        use_jwt.assert_not_called()
+
+
+@pytest.mark.parametrize(
+    "transport_class,transport_name",
+    [
+        (transports.ExecutionsGrpcTransport, "grpc"),
+        (transports.ExecutionsGrpcAsyncIOTransport, "grpc_asyncio"),
+    ],
+)
+def test_executions_client_service_account_always_use_jwt_true(
+    transport_class, transport_name
+):
+    with mock.patch.object(
+        service_account.Credentials, "with_always_use_jwt_access", create=True
+    ) as use_jwt:
+        creds = service_account.Credentials(None, None, None)
+        transport = transport_class(credentials=creds, always_use_jwt_access=True)
+        use_jwt.assert_called_once_with(True)
 
 
 @pytest.mark.parametrize("client_class", [ExecutionsClient, ExecutionsAsyncClient,])
@@ -1723,7 +1741,7 @@ def test_executions_grpc_transport_client_cert_source_for_mtls(transport_class):
             "squid.clam.whelk:443",
             credentials=cred,
             credentials_file=None,
-            scopes=("https://www.googleapis.com/auth/cloud-platform",),
+            scopes=None,
             ssl_credentials=mock_ssl_channel_creds,
             quota_project_id=None,
             options=[
@@ -1827,7 +1845,7 @@ def test_executions_transport_channel_mtls_with_client_cert_source(transport_cla
                 "mtls.squid.clam.whelk:443",
                 credentials=cred,
                 credentials_file=None,
-                scopes=("https://www.googleapis.com/auth/cloud-platform",),
+                scopes=None,
                 ssl_credentials=mock_ssl_cred,
                 quota_project_id=None,
                 options=[
@@ -1871,7 +1889,7 @@ def test_executions_transport_channel_mtls_with_adc(transport_class):
                 "mtls.squid.clam.whelk:443",
                 credentials=mock_cred,
                 credentials_file=None,
-                scopes=("https://www.googleapis.com/auth/cloud-platform",),
+                scopes=None,
                 ssl_credentials=mock_ssl_cred,
                 quota_project_id=None,
                 options=[
diff --git a/tests/unit/gapic/executions_v1beta/test_executions.py b/tests/unit/gapic/executions_v1beta/test_executions.py
index 1174a5b..c63f9d1 100644
--- a/tests/unit/gapic/executions_v1beta/test_executions.py
+++ b/tests/unit/gapic/executions_v1beta/test_executions.py
@@ -125,7 +125,25 @@ def test_executions_client_service_account_always_use_jwt(client_class):
     ) as use_jwt:
         creds = service_account.Credentials(None, None, None)
         client = client_class(credentials=creds)
-        use_jwt.assert_called_with(True)
+        use_jwt.assert_not_called()
+
+
+@pytest.mark.parametrize(
+    "transport_class,transport_name",
+    [
+        (transports.ExecutionsGrpcTransport, "grpc"),
+        (transports.ExecutionsGrpcAsyncIOTransport, "grpc_asyncio"),
+    ],
+)
+def test_executions_client_service_account_always_use_jwt_true(
+    transport_class, transport_name
+):
+    with mock.patch.object(
+        service_account.Credentials, "with_always_use_jwt_access", create=True
+    ) as use_jwt:
+        creds = service_account.Credentials(None, None, None)
+        transport = transport_class(credentials=creds, always_use_jwt_access=True)
+        use_jwt.assert_called_once_with(True)
 
 
 @pytest.mark.parametrize("client_class", [ExecutionsClient, ExecutionsAsyncClient,])
@@ -1725,7 +1743,7 @@ def test_executions_grpc_transport_client_cert_source_for_mtls(transport_class):
             "squid.clam.whelk:443",
             credentials=cred,
             credentials_file=None,
-            scopes=("https://www.googleapis.com/auth/cloud-platform",),
+            scopes=None,
             ssl_credentials=mock_ssl_channel_creds,
             quota_project_id=None,
             options=[
@@ -1829,7 +1847,7 @@ def test_executions_transport_channel_mtls_with_client_cert_source(transport_cla
                 "mtls.squid.clam.whelk:443",
                 credentials=cred,
                 credentials_file=None,
-                scopes=("https://www.googleapis.com/auth/cloud-platform",),
+                scopes=None,
                 ssl_credentials=mock_ssl_cred,
                 quota_project_id=None,
                 options=[
@@ -1873,7 +1891,7 @@ def test_executions_transport_channel_mtls_with_adc(transport_class):
                 "mtls.squid.clam.whelk:443",
                 credentials=mock_cred,
                 credentials_file=None,
-                scopes=("https://www.googleapis.com/auth/cloud-platform",),
+                scopes=None,
                 ssl_credentials=mock_ssl_cred,
                 quota_project_id=None,
                 options=[
diff --git a/tests/unit/gapic/workflows_v1/test_workflows.py b/tests/unit/gapic/workflows_v1/test_workflows.py
index 75eea88..59e72d0 100644
--- a/tests/unit/gapic/workflows_v1/test_workflows.py
+++ b/tests/unit/gapic/workflows_v1/test_workflows.py
@@ -124,7 +124,25 @@ def test_workflows_client_service_account_always_use_jwt(client_class):
     ) as use_jwt:
         creds = service_account.Credentials(None, None, None)
         client = client_class(credentials=creds)
-        use_jwt.assert_called_with(True)
+        use_jwt.assert_not_called()
+
+
+@pytest.mark.parametrize(
+    "transport_class,transport_name",
+    [
+        (transports.WorkflowsGrpcTransport, "grpc"),
+        (transports.WorkflowsGrpcAsyncIOTransport, "grpc_asyncio"),
+    ],
+)
+def test_workflows_client_service_account_always_use_jwt_true(
+    transport_class, transport_name
+):
+    with mock.patch.object(
+        service_account.Credentials, "with_always_use_jwt_access", create=True
+    ) as use_jwt:
+        creds = service_account.Credentials(None, None, None)
+        transport = transport_class(credentials=creds, always_use_jwt_access=True)
+        use_jwt.assert_called_once_with(True)
 
 
 @pytest.mark.parametrize("client_class", [WorkflowsClient, WorkflowsAsyncClient,])
@@ -1904,7 +1922,7 @@ def test_workflows_grpc_transport_client_cert_source_for_mtls(transport_class):
             "squid.clam.whelk:443",
             credentials=cred,
             credentials_file=None,
-            scopes=("https://www.googleapis.com/auth/cloud-platform",),
+            scopes=None,
             ssl_credentials=mock_ssl_channel_creds,
             quota_project_id=None,
             options=[
@@ -2008,7 +2026,7 @@ def test_workflows_transport_channel_mtls_with_client_cert_source(transport_clas
                 "mtls.squid.clam.whelk:443",
                 credentials=cred,
                 credentials_file=None,
-                scopes=("https://www.googleapis.com/auth/cloud-platform",),
+                scopes=None,
                 ssl_credentials=mock_ssl_cred,
                 quota_project_id=None,
                 options=[
@@ -2052,7 +2070,7 @@ def test_workflows_transport_channel_mtls_with_adc(transport_class):
                 "mtls.squid.clam.whelk:443",
                 credentials=mock_cred,
                 credentials_file=None,
-                scopes=("https://www.googleapis.com/auth/cloud-platform",),
+                scopes=None,
                 ssl_credentials=mock_ssl_cred,
                 quota_project_id=None,
                 options=[
diff --git a/tests/unit/gapic/workflows_v1beta/test_workflows.py b/tests/unit/gapic/workflows_v1beta/test_workflows.py
index 46517be..36c4f2c 100644
--- a/tests/unit/gapic/workflows_v1beta/test_workflows.py
+++ b/tests/unit/gapic/workflows_v1beta/test_workflows.py
@@ -124,7 +124,25 @@ def test_workflows_client_service_account_always_use_jwt(client_class):
     ) as use_jwt:
         creds = service_account.Credentials(None, None, None)
         client = client_class(credentials=creds)
-        use_jwt.assert_called_with(True)
+        use_jwt.assert_not_called()
+
+
+@pytest.mark.parametrize(
+    "transport_class,transport_name",
+    [
+        (transports.WorkflowsGrpcTransport, "grpc"),
+        (transports.WorkflowsGrpcAsyncIOTransport, "grpc_asyncio"),
+    ],
+)
+def test_workflows_client_service_account_always_use_jwt_true(
+    transport_class, transport_name
+):
+    with mock.patch.object(
+        service_account.Credentials, "with_always_use_jwt_access", create=True
+    ) as use_jwt:
+        creds = service_account.Credentials(None, None, None)
+        transport = transport_class(credentials=creds, always_use_jwt_access=True)
+        use_jwt.assert_called_once_with(True)
 
 
 @pytest.mark.parametrize("client_class", [WorkflowsClient, WorkflowsAsyncClient,])
@@ -1904,7 +1922,7 @@ def test_workflows_grpc_transport_client_cert_source_for_mtls(transport_class):
             "squid.clam.whelk:443",
             credentials=cred,
             credentials_file=None,
-            scopes=("https://www.googleapis.com/auth/cloud-platform",),
+            scopes=None,
             ssl_credentials=mock_ssl_channel_creds,
             quota_project_id=None,
             options=[
@@ -2008,7 +2026,7 @@ def test_workflows_transport_channel_mtls_with_client_cert_source(transport_clas
                 "mtls.squid.clam.whelk:443",
                 credentials=cred,
                 credentials_file=None,
-                scopes=("https://www.googleapis.com/auth/cloud-platform",),
+                scopes=None,
                 ssl_credentials=mock_ssl_cred,
                 quota_project_id=None,
                 options=[
@@ -2052,7 +2070,7 @@ def test_workflows_transport_channel_mtls_with_adc(transport_class):
                 "mtls.squid.clam.whelk:443",
                 credentials=mock_cred,
                 credentials_file=None,
-                scopes=("https://www.googleapis.com/auth/cloud-platform",),
+                scopes=None,
                 ssl_credentials=mock_ssl_cred,
                 quota_project_id=None,
                 options=[