@@ -110,6 +110,7 @@ Routine
 .. autosummary::
 :toctree: generated
 
+routine.DeterminismLevel
 routine.Routine
 routine.RoutineArgument
 routine.RoutineReference

@@ -70,6 +70,7 @@
 from google.cloud.bigquery.query import StructQueryParameter
 from google.cloud.bigquery.query import UDFResource
 from google.cloud.bigquery.retry import DEFAULT_RETRY
+from google.cloud.bigquery.routine import DeterminismLevel
 from google.cloud.bigquery.routine import Routine
 from google.cloud.bigquery.routine import RoutineArgument
 from google.cloud.bigquery.routine import RoutineReference
@@ -134,6 +135,7 @@
 "Compression",
 "CreateDisposition",
 "DestinationFormat",
+"DeterminismLevel",
 "ExternalSourceFormat",
 "Encoding",
 "QueryPriority",

@@ -234,3 +234,20 @@ class WriteDisposition(object):
 WRITE_EMPTY = "WRITE_EMPTY"
 """If the table already exists and contains data, a 'duplicate' error is
 returned in the job result."""
+
+
+class DeterminismLevel:
+"""Specifies determinism level for JavaScript user-defined functions (UDFs).
+
+https://cloud.google.com/bigquery/docs/reference/rest/v2/routines#DeterminismLevel
+"""
+
+DETERMINISM_LEVEL_UNSPECIFIED = "DETERMINISM_LEVEL_UNSPECIFIED"
+"""The determinism of the UDF is unspecified."""
+
+DETERMINISTIC = "DETERMINISTIC"
+"""The UDF is deterministic, meaning that 2 function calls with the same inputs
+always produce the same result, even across 2 query runs."""
+
+NOT_DETERMINISTIC = "NOT_DETERMINISTIC"
+"""The UDF is not deterministic."""

@@ -0,0 +1,29 @@
+# Copyright 2021 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""User-Defined Routines."""
+
+
+from google.cloud.bigquery.enums import DeterminismLevel
+from google.cloud.bigquery.routine.routine import Routine
+from google.cloud.bigquery.routine.routine import RoutineArgument
+from google.cloud.bigquery.routine.routine import RoutineReference
+
+
+__all__ = (
+"DeterminismLevel",
+"Routine",
+"RoutineArgument",
+"RoutineReference",
+)

@@ -50,6 +50,7 @@ class Routine(object):
 "return_type": "returnType",
 "type_": "routineType",
 "description": "description",
+"determinism_level": "determinismLevel",
 }
 
 def __init__(self, routine_ref, **kwargs):
@@ -253,6 +254,17 @@ def description(self):
 def description(self, value):
 self._properties[self._PROPERTY_TO_API_FIELD["description"]] = value
 
+@property
+def determinism_level(self):
+"""Optional[str]: (experimental) The determinism level of the JavaScript UDF
+if defined.
+"""
+return self._properties.get(self._PROPERTY_TO_API_FIELD["determinism_level"])
+
+@determinism_level.setter
+def determinism_level(self, value):
+self._properties[self._PROPERTY_TO_API_FIELD["determinism_level"]] = value
+
 @classmethod
 def from_api_repr(cls, resource):
 """Factory: construct a routine given its API representation.

@@ -2682,6 +2682,7 @@ def test_create_routine(self):
 )
 ]
 routine.body = "return maxValue(arr)"
+routine.determinism_level = bigquery.DeterminismLevel.DETERMINISTIC
 query_string = "SELECT `{}`([-100.0, 3.14, 100.0, 42.0]) as max_value;".format(
 str(routine.reference)
 )

@@ -18,6 +18,7 @@
 import pytest
 
 import google.cloud._helpers
+from google.cloud import bigquery
 from google.cloud import bigquery_v2
 
 
@@ -73,6 +74,7 @@ def test_ctor_w_properties(target_class):
 )
 type_ = "SCALAR_FUNCTION"
 description = "A routine description."
+determinism_level = bigquery.DeterminismLevel.NOT_DETERMINISTIC
 
 actual_routine = target_class(
 routine_id,
@@ -82,6 +84,7 @@ def test_ctor_w_properties(target_class):
 return_type=return_type,
 type_=type_,
 description=description,
+determinism_level=determinism_level,
 )
 
 ref = RoutineReference.from_string(routine_id)
@@ -92,6 +95,9 @@ def test_ctor_w_properties(target_class):
 assert actual_routine.return_type == return_type
 assert actual_routine.type_ == type_
 assert actual_routine.description == description
+assert (
+actual_routine.determinism_level == bigquery.DeterminismLevel.NOT_DETERMINISTIC
+)
 
 
 def test_from_api_repr(target_class):
@@ -120,6 +126,7 @@ def test_from_api_repr(target_class):
 "routineType": "SCALAR_FUNCTION",
 "someNewField": "someValue",
 "description": "A routine description.",
+"determinismLevel": bigquery.DeterminismLevel.DETERMINISTIC,
 }
 actual_routine = target_class.from_api_repr(resource)
 
@@ -152,6 +159,7 @@ def test_from_api_repr(target_class):
 assert actual_routine.type_ == "SCALAR_FUNCTION"
 assert actual_routine._properties["someNewField"] == "someValue"
 assert actual_routine.description == "A routine description."
+assert actual_routine.determinism_level == "DETERMINISTIC"
 
 
 def test_from_api_repr_w_minimal_resource(target_class):
@@ -177,6 +185,7 @@ def test_from_api_repr_w_minimal_resource(target_class):
 assert actual_routine.return_type is None
 assert actual_routine.type_ is None
 assert actual_routine.description is None
+assert actual_routine.determinism_level is None
 
 
 def test_from_api_repr_w_unknown_fields(target_class):
@@ -208,6 +217,7 @@ def test_from_api_repr_w_unknown_fields(target_class):
 "returnType": {"typeKind": "INT64"},
 "routineType": "SCALAR_FUNCTION",
 "description": "A routine description.",
+"determinismLevel": bigquery.DeterminismLevel.DETERMINISM_LEVEL_UNSPECIFIED,
 },
 ["arguments"],
 {"arguments": [{"name": "x", "dataType": {"typeKind": "INT64"}}]},
@@ -220,6 +230,7 @@ def test_from_api_repr_w_unknown_fields(target_class):
 "returnType": {"typeKind": "INT64"},
 "routineType": "SCALAR_FUNCTION",
 "description": "A routine description.",
+"determinismLevel": bigquery.DeterminismLevel.DETERMINISM_LEVEL_UNSPECIFIED,
 },
 ["body"],
 {"definitionBody": "x * 3"},
@@ -232,6 +243,7 @@ def test_from_api_repr_w_unknown_fields(target_class):
 "returnType": {"typeKind": "INT64"},
 "routineType": "SCALAR_FUNCTION",
 "description": "A routine description.",
+"determinismLevel": bigquery.DeterminismLevel.DETERMINISM_LEVEL_UNSPECIFIED,
 },
 ["language"],
 {"language": "SQL"},
@@ -244,6 +256,7 @@ def test_from_api_repr_w_unknown_fields(target_class):
 "returnType": {"typeKind": "INT64"},
 "routineType": "SCALAR_FUNCTION",
 "description": "A routine description.",
+"determinismLevel": bigquery.DeterminismLevel.DETERMINISM_LEVEL_UNSPECIFIED,
 },
 ["return_type"],
 {"returnType": {"typeKind": "INT64"}},
@@ -256,6 +269,7 @@ def test_from_api_repr_w_unknown_fields(target_class):
 "returnType": {"typeKind": "INT64"},
 "routineType": "SCALAR_FUNCTION",
 "description": "A routine description.",
+"determinismLevel": bigquery.DeterminismLevel.DETERMINISM_LEVEL_UNSPECIFIED,
 },
 ["type_"],
 {"routineType": "SCALAR_FUNCTION"},
@@ -268,20 +282,45 @@ def test_from_api_repr_w_unknown_fields(target_class):
 "returnType": {"typeKind": "INT64"},
 "routineType": "SCALAR_FUNCTION",
 "description": "A routine description.",
+"determinismLevel": bigquery.DeterminismLevel.DETERMINISM_LEVEL_UNSPECIFIED,
 },
 ["description"],
 {"description": "A routine description."},
 ),
+(
+{
+"arguments": [{"name": "x", "dataType": {"typeKind": "INT64"}}],
+"definitionBody": "x * 3",
+"language": "SQL",
+"returnType": {"typeKind": "INT64"},
+"routineType": "SCALAR_FUNCTION",
+"description": "A routine description.",
+"determinismLevel": bigquery.DeterminismLevel.DETERMINISM_LEVEL_UNSPECIFIED,
+},
+["determinism_level"],
+{
+"determinismLevel": bigquery.DeterminismLevel.DETERMINISM_LEVEL_UNSPECIFIED
+},
+),
 (
 {},
-["arguments", "language", "body", "type_", "return_type", "description"],
+[
+"arguments",
+"language",
+"body",
+"type_",
+"return_type",
+"description",
+"determinism_level",
+],
 {
 "arguments": None,
 "definitionBody": None,
 "language": None,
 "returnType": None,
 "routineType": None,
 "description": None,
+"determinismLevel": None,
 },
 ),
 (