diff --git a/cinder/policy.py b/cinder/policy.py
index 5e863fd4f6a..f7c106a9e0a 100644
--- a/cinder/policy.py
+++ b/cinder/policy.py
@@ -16,6 +16,8 @@
 """Policy Engine For Cinder"""
 
 import sys
+import typing
+from typing import Optional, Type  # noqa: H301
 
 from oslo_config import cfg
 from oslo_log import log as logging
@@ -23,6 +25,8 @@ from oslo_policy import opts as policy_opts
 from oslo_policy import policy
 from oslo_utils import excutils
 
+
+from cinder import context
 from cinder import exception
 from cinder import policies
 
@@ -31,10 +35,10 @@ LOG = logging.getLogger(__name__)
 DEFAULT_POLICY_FILENAME = 'policy.yaml'
 policy_opts.set_defaults(cfg.CONF, DEFAULT_POLICY_FILENAME)
 
-_ENFORCER = None
+_ENFORCER: Optional[policy.Enforcer] = None
 
 
-def reset():
+def reset() -> None:
     global _ENFORCER
     if _ENFORCER:
         _ENFORCER.clear()
@@ -42,7 +46,7 @@ def reset():
 
 
 def init(use_conf=True,
-         suppress_deprecation_warnings=False):
+         suppress_deprecation_warnings: bool = False) -> None:
     """Init an Enforcer class.
 
     :param use_conf: Whether to load rules from config file.
@@ -58,8 +62,10 @@ def init(use_conf=True,
         register_rules(_ENFORCER)
         _ENFORCER.load_rules()
 
+    _ENFORCER = typing.cast(policy.Enforcer, _ENFORCER)
 
-def enforce(context, action, target):
+
+def enforce(context, action: str, target: dict):
     """Verifies that the action is valid on the target in this context.
 
     :param context: cinder context
@@ -77,6 +83,7 @@ def enforce(context, action, target):
     :raises PolicyNotAuthorized: if verification fails.
     """
     init()
+    assert _ENFORCER is not None
 
     try:
         return _ENFORCER.enforce(action,
@@ -89,7 +96,9 @@ def enforce(context, action, target):
         raise exception.PolicyNotAuthorized(action=action)
 
 
-def set_rules(rules, overwrite=True, use_conf=False):
+def set_rules(rules: dict,
+              overwrite: bool = True,
+              use_conf: bool = False) -> None:
     """Set rules based on the provided dict of rules.
 
     :param rules: New rules to use. It should be an instance of dict.
@@ -99,6 +108,8 @@ def set_rules(rules, overwrite=True, use_conf=False):
     """
 
     init(use_conf=False)
+    assert _ENFORCER is not None
+
     _ENFORCER.set_rules(rules, overwrite, use_conf)
 
 
@@ -111,7 +122,7 @@ def register_rules(enforcer):
     enforcer.register_defaults(policies.list_rules())
 
 
-def get_enforcer():
+def get_enforcer() -> policy.Enforcer:
     # This method is for use by oslopolicy CLI scripts. Those scripts need the
     # 'output-file' and 'namespace' options, but having those in sys.argv means
     # loading the Cinder config options will fail as those are not expected to
@@ -128,10 +139,15 @@ def get_enforcer():
 
     cfg.CONF(conf_args, project='cinder')
     init()
+    assert _ENFORCER is not None
     return _ENFORCER
 
 
-def authorize(context, action, target, do_raise=True, exc=None):
+def authorize(context,
+              action: str,
+              target: dict,
+              do_raise: bool = True,
+              exc: Optional[Type[Exception]] = None):
     """Verifies that the action is valid on the target in this context.
 
     :param context: cinder context
@@ -161,6 +177,8 @@ def authorize(context, action, target, do_raise=True, exc=None):
              do_raise is False.
     """
     init()
+    assert _ENFORCER is not None
+
     if not exc:
         exc = exception.PolicyNotAuthorized
     try:
@@ -178,9 +196,11 @@ def authorize(context, action, target, do_raise=True, exc=None):
     return result
 
 
-def check_is_admin(context):
+def check_is_admin(context: 'context.RequestContext'):
     """Whether or not user is admin according to policy setting."""
     init()
+    assert _ENFORCER is not None
+
     # the target is user-self
     credentials = context.to_policy_values()
     target = credentials
diff --git a/mypy-files.txt b/mypy-files.txt
index 27587898a7b..dfae267dc9e 100644
--- a/mypy-files.txt
+++ b/mypy-files.txt
@@ -11,6 +11,7 @@ cinder/image/image_utils.py
 cinder/exception.py
 cinder/manager.py
 cinder/objects/backup.py
+cinder/policy.py
 cinder/scheduler/base_handler.py
 cinder/scheduler/base_weight.py
 cinder/scheduler/evaluator/evaluator.py