diff --git a/CHANGELOG b/CHANGELOG
index 2321a83d6..c6cb8ac59 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -20,6 +20,12 @@ Core:
 - No reload on logoff. OpenSlides is now a full single page
   application [#3172].
 
+Users:
+- User without permission to see users can now see agenda item speakers,
+  motion submitters and supporters, assignment candidates, mediafile
+  uploader and chat message users if they have the respective
+  permissions [#3191].
+
 
 Version 2.1.1 (2017-04-05)
 ==========================
diff --git a/openslides/agenda/apps.py b/openslides/agenda/apps.py
index 2a7087bbd..429c808d2 100644
--- a/openslides/agenda/apps.py
+++ b/openslides/agenda/apps.py
@@ -17,11 +17,12 @@ class AgendaAppConfig(AppConfig):
         # Import all required stuff.
         from django.db.models.signals import pre_delete, post_save
         from openslides.core.config import config
-        from openslides.core.signals import permission_change
+        from openslides.core.signals import permission_change, user_data_required
         from openslides.utils.rest_api import router
         from .config_variables import get_config_variables
         from .signals import (
             get_permission_change_data,
+            is_user_data_required,
             listen_to_related_object_post_delete,
             listen_to_related_object_post_save)
         from .views import ItemViewSet
@@ -39,6 +40,9 @@ class AgendaAppConfig(AppConfig):
         permission_change.connect(
             get_permission_change_data,
             dispatch_uid='agenda_get_permission_change_data')
+        user_data_required.connect(
+            is_user_data_required,
+            dispatch_uid='agenda_is_user_data_required')
 
         # Register viewsets.
         router.register(self.get_model('Item').get_collection_string(), ItemViewSet)
diff --git a/openslides/agenda/signals.py b/openslides/agenda/signals.py
index 2e2064942..4d76dfced 100644
--- a/openslides/agenda/signals.py
+++ b/openslides/agenda/signals.py
@@ -1,8 +1,9 @@
 from django.apps import apps
 from django.contrib.contenttypes.models import ContentType
 
-from openslides.utils.autoupdate import inform_changed_data
-
+from ..utils.auth import has_perm
+from ..utils.autoupdate import inform_changed_data
+from ..utils.collection import Collection
 from .models import Item
 
 
@@ -51,3 +52,22 @@ def get_permission_change_data(sender, permissions, **kwargs):
                 and permission.codename in ('can_see', 'can_see_hidden_items')):
             yield from agenda_app.get_startup_elements()
             break
+
+
+def is_user_data_required(sender, request_user, user_data, **kwargs):
+    """
+    Returns True if request user can see the agenda and user_data is required
+    to be displayed as speaker.
+    """
+    result = False
+    if has_perm(request_user, 'agenda.can_see'):
+        for item_collection_element in Collection(Item.get_collection_string()).element_generator():
+            full_data = item_collection_element.get_full_data()
+            for speaker in full_data['speakers']:
+                if user_data['id'] == speaker['user_id']:
+                    result = True
+                    break
+            else:
+                continue
+            break
+    return result
diff --git a/openslides/assignments/apps.py b/openslides/assignments/apps.py
index 16634c46e..ebaba1d22 100644
--- a/openslides/assignments/apps.py
+++ b/openslides/assignments/apps.py
@@ -16,10 +16,10 @@ class AssignmentsAppConfig(AppConfig):
 
         # Import all required stuff.
         from openslides.core.config import config
-        from openslides.core.signals import permission_change
+        from openslides.core.signals import permission_change, user_data_required
         from openslides.utils.rest_api import router
         from .config_variables import get_config_variables
-        from .signals import get_permission_change_data
+        from .signals import get_permission_change_data, is_user_data_required
         from .views import AssignmentViewSet, AssignmentPollViewSet
 
         # Define config variables
@@ -29,6 +29,9 @@ class AssignmentsAppConfig(AppConfig):
         permission_change.connect(
             get_permission_change_data,
             dispatch_uid='assignments_get_permission_change_data')
+        user_data_required.connect(
+            is_user_data_required,
+            dispatch_uid='assignments_is_user_data_required')
 
         # Register viewsets.
         router.register(self.get_model('Assignment').get_collection_string(), AssignmentViewSet)
diff --git a/openslides/assignments/signals.py b/openslides/assignments/signals.py
index 22182ba51..0bd2bf8b6 100644
--- a/openslides/assignments/signals.py
+++ b/openslides/assignments/signals.py
@@ -1,5 +1,9 @@
 from django.apps import apps
 
+from ..utils.auth import has_perm
+from ..utils.collection import Collection
+from .models import Assignment
+
 
 def get_permission_change_data(sender, permissions=None, **kwargs):
     """
@@ -10,3 +14,32 @@ def get_permission_change_data(sender, permissions=None, **kwargs):
         # There could be only one 'assignment.can_see' and then we want to return data.
         if permission.content_type.app_label == assignments_app.label and permission.codename == 'can_see':
             yield from assignments_app.get_startup_elements()
+
+
+def is_user_data_required(sender, request_user, user_data, **kwargs):
+    """
+    Returns True if request user can see assignments and user_data is required
+    to be displayed as candidates (including poll options).
+    """
+    result = False
+    if has_perm(request_user, 'assignments.can_see'):
+        for assignment_collection_element in Collection(Assignment.get_collection_string()).element_generator():
+            full_data = assignment_collection_element.get_full_data()
+            for related_user in full_data['assignment_related_users']:
+                if user_data['id'] == related_user['user_id']:
+                    result = True
+                    break
+            else:
+                for poll in full_data['polls']:
+                    for option in poll['options']:
+                        if user_data['id'] == option['candidate_id']:
+                            result = True
+                            break
+                    else:
+                        continue
+                    break
+                else:
+                    continue
+                break
+            break
+    return result
diff --git a/openslides/core/apps.py b/openslides/core/apps.py
index 389316682..f58570467 100644
--- a/openslides/core/apps.py
+++ b/openslides/core/apps.py
@@ -23,7 +23,9 @@ class CoreAppConfig(AppConfig):
         from .signals import (
             delete_django_app_permissions,
             get_permission_change_data,
-            permission_change)
+            is_user_data_required,
+            permission_change,
+            user_data_required)
         from .views import (
             ChatMessageViewSet,
             ConfigViewSet,
@@ -43,6 +45,9 @@ class CoreAppConfig(AppConfig):
         permission_change.connect(
             get_permission_change_data,
             dispatch_uid='core_get_permission_change_data')
+        user_data_required.connect(
+            is_user_data_required,
+            dispatch_uid='core_is_user_data_required')
 
         # Register viewsets.
         router.register(self.get_model('Projector').get_collection_string(), ProjectorViewSet)
diff --git a/openslides/core/signals.py b/openslides/core/signals.py
index 2d3f2f8e7..c14c42037 100644
--- a/openslides/core/signals.py
+++ b/openslides/core/signals.py
@@ -4,7 +4,9 @@ from django.contrib.contenttypes.models import ContentType
 from django.db.models import Q
 from django.dispatch import Signal
 
+from ..utils.auth import has_perm
 from ..utils.collection import Collection
+from .models import ChatMessage
 
 # This signal is send when the migrate command is done. That means it is sent
 # after post_migrate sending and creating all Permission objects. Don't use it
@@ -15,6 +17,12 @@ post_permission_creation = Signal()
 # permission). Connected receivers may yield Collections.
 permission_change = Signal()
 
+# This signal is sent if someone wants to see basic user data. Connected
+# receivers may answer True if the user data is required for the request user
+# (this can be anything that is allowd as argument for utils.auth.has_perm())
+# e. g. as motion submitter or assignment candidate.
+user_data_required = Signal(providing_args=['request_user', 'user_data'])
+
 
 def delete_django_app_permissions(sender, **kwargs):
     """
@@ -42,3 +50,18 @@ def get_permission_change_data(sender, permissions, **kwargs):
                 yield Collection(core_app.get_model('Countdown').get_collection_string())
             elif permission.codename == 'can_use_chat':
                 yield Collection(core_app.get_model('ChatMessage').get_collection_string())
+
+
+def is_user_data_required(sender, request_user, user_data, **kwargs):
+    """
+    Returns True if request user can use chat and user_data is required
+    to be displayed as chatter.
+    """
+    result = False
+    if has_perm(request_user, 'core.can_use_chat'):
+        for chat_message_collection_element in Collection(ChatMessage.get_collection_string()).element_generator():
+            full_data = chat_message_collection_element.get_full_data()
+            if user_data['id'] == full_data['user_id']:
+                result = True
+                break
+    return result
diff --git a/openslides/mediafiles/apps.py b/openslides/mediafiles/apps.py
index 76ef8b5b6..c59303576 100644
--- a/openslides/mediafiles/apps.py
+++ b/openslides/mediafiles/apps.py
@@ -15,15 +15,18 @@ class MediafilesAppConfig(AppConfig):
         from . import projector  # noqa
 
         # Import all required stuff.
-        from openslides.core.signals import permission_change
+        from openslides.core.signals import permission_change, user_data_required
         from openslides.utils.rest_api import router
-        from .signals import get_permission_change_data
+        from .signals import get_permission_change_data, is_user_data_required
         from .views import MediafileViewSet
 
         # Connect signals.
         permission_change.connect(
             get_permission_change_data,
             dispatch_uid='mediafiles_get_permission_change_data')
+        user_data_required.connect(
+            is_user_data_required,
+            dispatch_uid='mediafiles_is_user_data_required')
 
         # Register viewsets.
         router.register(self.get_model('Mediafile').get_collection_string(), MediafileViewSet)
diff --git a/openslides/mediafiles/signals.py b/openslides/mediafiles/signals.py
index ad297ac19..ca333da33 100644
--- a/openslides/mediafiles/signals.py
+++ b/openslides/mediafiles/signals.py
@@ -1,5 +1,9 @@
 from django.apps import apps
 
+from ..utils.auth import has_perm
+from ..utils.collection import Collection
+from .models import Mediafile
+
 
 def get_permission_change_data(sender, permissions=None, **kwargs):
     """
@@ -10,3 +14,18 @@ def get_permission_change_data(sender, permissions=None, **kwargs):
         # There could be only one 'mediafiles.can_see' and then we want to return data.
         if permission.content_type.app_label == mediafiles_app.label and permission.codename == 'can_see':
             yield from mediafiles_app.get_startup_elements()
+
+
+def is_user_data_required(sender, request_user, user_data, **kwargs):
+    """
+    Returns True if request user can see mediafiles and user_data is required
+    to be displayed as uploader.
+    """
+    result = False
+    if has_perm(request_user, 'mediafiles.can_see'):
+        for mediafile_collection_element in Collection(Mediafile.get_collection_string()).element_generator():
+            full_data = mediafile_collection_element.get_full_data()
+            if user_data['id'] == full_data['uploader_id']:
+                result = True
+                break
+    return result
diff --git a/openslides/motions/apps.py b/openslides/motions/apps.py
index 45f904875..792a09d71 100644
--- a/openslides/motions/apps.py
+++ b/openslides/motions/apps.py
@@ -17,10 +17,10 @@ class MotionsAppConfig(AppConfig):
 
         # Import all required stuff.
         from openslides.core.config import config
-        from openslides.core.signals import permission_change
+        from openslides.core.signals import permission_change, user_data_required
         from openslides.utils.rest_api import router
         from .config_variables import get_config_variables
-        from .signals import create_builtin_workflows, get_permission_change_data
+        from .signals import create_builtin_workflows, get_permission_change_data, is_user_data_required
         from .views import CategoryViewSet, MotionViewSet, MotionBlockViewSet, MotionPollViewSet, MotionChangeRecommendationViewSet, WorkflowViewSet
 
         # Define config variables
@@ -31,6 +31,9 @@ class MotionsAppConfig(AppConfig):
         permission_change.connect(
             get_permission_change_data,
             dispatch_uid='motions_get_permission_change_data')
+        user_data_required.connect(
+            is_user_data_required,
+            dispatch_uid='motions_is_user_data_required')
 
         # Register viewsets.
         router.register(self.get_model('Category').get_collection_string(), CategoryViewSet)
diff --git a/openslides/motions/signals.py b/openslides/motions/signals.py
index 64a0cdb9e..087a2b13b 100644
--- a/openslides/motions/signals.py
+++ b/openslides/motions/signals.py
@@ -1,7 +1,9 @@
 from django.apps import apps
 from django.utils.translation import ugettext_noop
 
-from .models import State, Workflow
+from ..utils.auth import has_perm
+from ..utils.collection import Collection
+from .models import Motion, State, Workflow
 
 
 def create_builtin_workflows(sender, **kwargs):
@@ -114,3 +116,18 @@ def get_permission_change_data(sender, permissions, **kwargs):
         # There could be only one 'motions.can_see' and then we want to return data.
         if permission.content_type.app_label == motions_app.label and permission.codename == 'can_see':
             yield from motions_app.get_startup_elements()
+
+
+def is_user_data_required(sender, request_user, user_data, **kwargs):
+    """
+    Returns True if request user can see motions and user_data is required
+    to be displayed as motion submitter or supporter.
+    """
+    result = False
+    if has_perm(request_user, 'motions.can_see'):
+        for motion_collection_element in Collection(Motion.get_collection_string()).element_generator():
+            full_data = motion_collection_element.get_full_data()
+            if user_data['id'] in full_data['submitters_id'] or user_data['id'] in full_data['supporters_id']:
+                result = True
+                break
+    return result
diff --git a/openslides/users/access_permissions.py b/openslides/users/access_permissions.py
index a33efa10a..86ed0d1a5 100644
--- a/openslides/users/access_permissions.py
+++ b/openslides/users/access_permissions.py
@@ -1,5 +1,6 @@
 from django.contrib.auth.models import AnonymousUser
 
+from ..core.signals import user_data_required
 from ..utils.access_permissions import BaseAccessPermissions
 from ..utils.auth import anonymous_is_enabled, has_perm
 
@@ -49,7 +50,18 @@ class UserAccessPermissions(BaseAccessPermissions):
             # to see himself.
             case = LITTLE_DATA
         else:
-            case = NO_DATA
+            # Now check if the user to be sent out is required by any app e. g.
+            # as motion submitter or assignment candidate.
+            receiver_responses = user_data_required.send(
+                sender=self.__class__,
+                request_user=user,
+                user_data=full_data)
+            for receiver, response in receiver_responses:
+                if response:
+                    case = LITTLE_DATA
+                    break
+            else:
+                case = NO_DATA
 
         # Setup data.
         if case == FULL_DATA:
diff --git a/tests/integration/motions/test_viewset.py b/tests/integration/motions/test_viewset.py
index b770152fc..0807cfbd5 100644
--- a/tests/integration/motions/test_viewset.py
+++ b/tests/integration/motions/test_viewset.py
@@ -413,6 +413,27 @@ class RetrieveMotion(TestCase):
         response = submitter_client.get(reverse('motion-detail', args=[self.motion.pk]))
         self.assertEqual(response.status_code, status.HTTP_200_OK)
 
+    def test_user_without_can_see_user_permission_to_see_motion_and_submitter_data(self):
+        self.motion.submitters.add(get_user_model().objects.get(username='admin'))
+        group = get_user_model().groups.field.related_model.objects.get(pk=1)  # Group with pk 1 is for anonymous and default users.
+        permission_string = 'users.can_see_name'
+        app_label, codename = permission_string.split('.')
+        permission = group.permissions.get(content_type__app_label=app_label, codename=codename)
+        group.permissions.remove(permission)
+        config['general_system_enable_anonymous'] = True
+        guest_client = APIClient()
+
+        response_1 = guest_client.get(reverse('motion-detail', args=[self.motion.pk]))
+        self.assertEqual(response_1.status_code, status.HTTP_200_OK)
+        response_2 = guest_client.get(reverse('user-detail', args=[response_1.data['submitters_id'][0]]))
+        self.assertEqual(response_2.status_code, status.HTTP_200_OK)
+
+        extra_user = get_user_model().objects.create_user(
+            username='username_wequePhieFoom0hai3wa',
+            password='password_ooth7taechai5Oocieya')
+        response_3 = guest_client.get(reverse('user-detail', args=[extra_user.pk]))
+        self.assertEqual(response_3.status_code, status.HTTP_403_FORBIDDEN)
+
 
 class UpdateMotion(TestCase):
     """
diff --git a/tests/integration/users/test_viewset.py b/tests/integration/users/test_viewset.py
index 859ab0b1a..43856a750 100644
--- a/tests/integration/users/test_viewset.py
+++ b/tests/integration/users/test_viewset.py
@@ -103,6 +103,19 @@ class UserGetTest(TestCase):
 
         self.assertEqual(response.status_code, 200)
 
+    def test_get_with_user_without_permissions(self):
+        group = Group.objects.get(pk=1)
+        permission_string = 'users.can_see_name'
+        app_label, codename = permission_string.split('.')
+        permission = group.permissions.get(content_type__app_label=app_label, codename=codename)
+        group.permissions.remove(permission)
+        config['general_system_enable_anonymous'] = True
+        guest_client = APIClient()
+
+        response = guest_client.get('/rest/users/user/1/')
+
+        self.assertEqual(response.status_code, 403)
+
 
 class UserCreate(TestCase):
     """