diff --git a/src/backend/api/v1/reviews/endpoints.py b/src/backend/api/v1/reviews/endpoints.py
index 444702a..5d6323b 100644
--- a/src/backend/api/v1/reviews/endpoints.py
+++ b/src/backend/api/v1/reviews/endpoints.py
@@ -1,4 +1,5 @@
 from http import HTTPStatus
+from uuid import UUID
 
 from django.core.exceptions import ValidationError
 from django.http import Http404, HttpRequest
@@ -101,7 +102,7 @@ def create_approver_group(
 @require_admin
 def get_approver_group(
     request: HttpRequest,
-    group_id: str,
+    group_id: UUID,
 ) -> tuple[HTTPStatus, ApproverGroupOut]:
     group = get_object_or_404(
         ApproverGroup.objects.select_related("experimenter").prefetch_related(
@@ -124,7 +125,7 @@ def get_approver_group(
 @require_admin
 def update_approver_group(
     request: HttpRequest,
-    group_id: str,
+    group_id: UUID,
     payload: ApproverGroupUpdateIn,
 ) -> tuple[HTTPStatus, ApproverGroupOut]:
     group = get_object_or_404(
@@ -160,7 +161,7 @@ def update_approver_group(
 @require_admin
 def delete_approver_group(
     request: HttpRequest,
-    group_id: str,
+    group_id: UUID,
 ) -> tuple[HTTPStatus, None]:
     group = get_object_or_404(
         ApproverGroup.objects.select_related("experimenter").prefetch_related(
@@ -184,7 +185,7 @@ def delete_approver_group(
 @require_admin
 def add_approver_to_group(
     request: HttpRequest,
-    group_id: str,
+    group_id: UUID,
     payload: ApproverGroupAddApproverIn,
 ) -> tuple[HTTPStatus, ApproverGroupOut]:
     group = get_object_or_404(
@@ -218,7 +219,7 @@ def add_approver_to_group(
 @require_admin
 def remove_approver_from_group(
     request: HttpRequest,
-    group_id: str,
+    group_id: UUID,
     payload: ApproverGroupRemoveApproverIn,
 ) -> tuple[HTTPStatus, ApproverGroupOut]:
     group = get_object_or_404(
@@ -252,9 +253,9 @@ def remove_approver_from_group(
 @require_admin
 def get_approver_group_by_experimenter(
     request: HttpRequest,
-    experimenter_id: str,
+    experimenter_id: UUID,
 ) -> tuple[HTTPStatus, ApproverGroupOut]:
-    group = approver_group_get_by_experimenter_id(experimenter_id)
+    group = approver_group_get_by_experimenter_id(str(experimenter_id))
     if group is None:
         raise Http404
 
@@ -311,7 +312,7 @@ def update_review_settings(
 )
 def get_effective_policy(
     request: HttpRequest,
-    experimenter_id: str,
+    experimenter_id: UUID,
 ) -> tuple[HTTPStatus, EffectiveReviewPolicyOut]:
     experimenter = get_object_or_404(User, pk=experimenter_id)
 
@@ -330,7 +331,7 @@ def get_effective_policy(
     )
 
     has_group = (
-        approver_group_get_by_experimenter_id(experimenter_id) is not None
+        approver_group_get_by_experimenter_id(str(experimenter_id)) is not None
     )
 
     return HTTPStatus.OK, EffectiveReviewPolicyOut(
diff --git a/src/backend/api/v1/users/endpoints.py b/src/backend/api/v1/users/endpoints.py
index 1bff7be..9ece296 100644
--- a/src/backend/api/v1/users/endpoints.py
+++ b/src/backend/api/v1/users/endpoints.py
@@ -1,4 +1,5 @@
 from http import HTTPStatus
+from uuid import UUID
 
 from django.core.exceptions import ValidationError
 from django.http import HttpRequest
@@ -81,7 +82,7 @@ def create_user(
 @require_admin
 def get_user(
     request: HttpRequest,
-    user_id: str,
+    user_id: UUID,
 ) -> tuple[HTTPStatus, UserOut]:
     user = get_object_or_404(User, pk=user_id)
     return HTTPStatus.OK, UserOut.model_validate(user)
@@ -100,7 +101,7 @@ def get_user(
 @require_admin
 def update_user(
     request: HttpRequest,
-    user_id: str,
+    user_id: UUID,
     payload: UserUpdateIn,
 ) -> tuple[HTTPStatus, UserOut]:
     user = get_object_or_404(User, pk=user_id)
@@ -119,7 +120,7 @@ def update_user(
 @require_admin
 def delete_user(
     request: HttpRequest,
-    user_id: str,
+    user_id: UUID,
 ) -> tuple[HTTPStatus, None]:
     user = get_object_or_404(User, pk=user_id)
 
@@ -144,7 +145,7 @@ def delete_user(
 @require_admin
 def assign_role(
     request: HttpRequest,
-    user_id: str,
+    user_id: UUID,
     payload: UserRoleAssignIn,
 ) -> tuple[HTTPStatus, UserOut]:
     user = get_object_or_404(User, pk=user_id)
diff --git a/src/backend/apps/reviews/services.py b/src/backend/apps/reviews/services.py
index 19ce1d2..22aa199 100644
--- a/src/backend/apps/reviews/services.py
+++ b/src/backend/apps/reviews/services.py
@@ -1,11 +1,11 @@
 from typing import Any
 
-from config.errors import ConflictError
 from django.core.exceptions import ValidationError
 from django.db import transaction
 
 from apps.reviews.models import ApproverGroup, ReviewSettings
 from apps.users.models import User, UserRole
+from config.errors import ConflictError
 
 
 def review_settings_update(