diff --git a/modules/civiremote_case/civiremote_case.permissions.yml b/modules/civiremote_case/civiremote_case.permissions.yml
new file mode 100644
index 0000000..42042a4
--- /dev/null
+++ b/modules/civiremote_case/civiremote_case.permissions.yml
@@ -0,0 +1,2 @@
+access civiremote case:
+  title: 'Access Cases in CiviCRM'
diff --git a/modules/civiremote_case/civiremote_case.routing.yml b/modules/civiremote_case/civiremote_case.routing.yml
index 8bbcb72..5965d75 100644
--- a/modules/civiremote_case/civiremote_case.routing.yml
+++ b/modules/civiremote_case/civiremote_case.routing.yml
@@ -8,7 +8,7 @@ civiremote_case.create_form:
       profile:
         type: string
   requirements:
-    _user_is_logged_in: 'TRUE'
+    _permission: 'access civiremote case'
 
 civiremote_case.update_form:
   path: '/civiremote/case/{id}/update/{profile}'
@@ -22,4 +22,4 @@ civiremote_case.update_form:
       profile:
         type: string
   requirements:
-    _user_is_logged_in: 'TRUE'
+    _permission: 'access civiremote case'
diff --git a/modules/civiremote_entity/src/Access/RemoteContactIdProvider.php b/modules/civiremote_entity/src/Access/RemoteContactIdProvider.php
index bf734d7..d3f24f4 100644
--- a/modules/civiremote_entity/src/Access/RemoteContactIdProvider.php
+++ b/modules/civiremote_entity/src/Access/RemoteContactIdProvider.php
@@ -20,7 +20,6 @@
 
 namespace Drupal\civiremote_entity\Access;
 
-use Assert\Assertion;
 use Drupal\Core\Session\AccountProxyInterface;
 
 final class RemoteContactIdProvider implements RemoteContactIdProviderInterface {
@@ -31,16 +30,33 @@ public function __construct(AccountProxyInterface $currentUser) {
     $this->currentUser = $currentUser;
   }
 
+  /**
+   * @{inheritDoc}
+   */
   public function getRemoteContactId(): string {
-    $account = $this->currentUser->getAccount();
-    Assertion::propertyExists($account, 'civiremote_id');
-    // @phpstan-ignore-next-line
-    $remoteContactId = $account->civiremote_id;
+    if (!$this->hasRemoteContactId()) {
+      throw new \RuntimeException(sprintf('User "%s" has no remote contact ID', $this->currentUser->getAccountName()));
+    }
+
+    // @phpstan-ignore property.notFound
+    return $this->currentUser->getAccount()->civiremote_id;
+  }
 
-    Assertion::string($remoteContactId);
-    Assertion::notEmpty($remoteContactId);
+  /**
+   * @{inheritDoc}
+   */
+  public function getRemoteContactIdOrNull(): ?string {
+    return $this->hasRemoteContactId() ? $this->getRemoteContactId() : NULL;
+  }
+
+  /**
+   * @{inheritDoc}
+   */
+  public function hasRemoteContactId(): bool {
+    $account = $this->currentUser->getAccount();
+    $remoteContactId = $account->civiremote_id ?? NULL;
 
-    return $remoteContactId;
+    return is_string($remoteContactId) && '' !== $remoteContactId;
   }
 
 }
diff --git a/modules/civiremote_entity/src/Access/RemoteContactIdProviderInterface.php b/modules/civiremote_entity/src/Access/RemoteContactIdProviderInterface.php
index 787c421..a952878 100644
--- a/modules/civiremote_entity/src/Access/RemoteContactIdProviderInterface.php
+++ b/modules/civiremote_entity/src/Access/RemoteContactIdProviderInterface.php
@@ -22,6 +22,19 @@
 
 interface RemoteContactIdProviderInterface {
 
+  /**
+   * @throws \RuntimeException
+   *   If current user has no remote contact ID.
+   */
   public function getRemoteContactId(): string;
 
+  /**
+   * @return string|null
+   *   The user's remote contact ID, or NULL if the user has no remote contact
+   *   ID.
+   */
+  public function getRemoteContactIdOrNull(): ?string;
+
+  public function hasRemoteContactId(): bool;
+
 }
diff --git a/modules/civiremote_entity/src/Api/AbstractEntityApi.php b/modules/civiremote_entity/src/Api/AbstractEntityApi.php
index 9cd5505..20dc99f 100644
--- a/modules/civiremote_entity/src/Api/AbstractEntityApi.php
+++ b/modules/civiremote_entity/src/Api/AbstractEntityApi.php
@@ -46,7 +46,7 @@ public function getCreateForm(string $profile, array $arguments = []): EntityFor
     $result = $this->client->executeV4($this->getRemoteEntityName(), 'getCreateForm', [
       'profile' => $profile,
       'arguments' => $arguments,
-      'remoteContactId' => $this->remoteContactIdProvider->getRemoteContactId(),
+      'remoteContactId' => $this->remoteContactIdProvider->getRemoteContactIdOrNull(),
     ]);
 
     return EntityForm::fromApiResultValue($result['values']);
@@ -61,7 +61,7 @@ public function submitCreateForm(string $profile, array $data, array $arguments
       'profile' => $profile,
       'data' => $data,
       'arguments' => $arguments,
-      'remoteContactId' => $this->remoteContactIdProvider->getRemoteContactId(),
+      'remoteContactId' => $this->remoteContactIdProvider->getRemoteContactIdOrNull(),
     ]);
 
     return FormSubmitResponse::fromApiResultValue($result['values']);
@@ -76,7 +76,7 @@ public function validateCreateForm(string $profile, array $data, array $argument
       'profile' => $profile,
       'data' => $data,
       'arguments' => $arguments,
-      'remoteContactId' => $this->remoteContactIdProvider->getRemoteContactId(),
+      'remoteContactId' => $this->remoteContactIdProvider->getRemoteContactIdOrNull(),
     ]);
 
     return FormValidationResponse::fromApiResultValue($result['values']);
@@ -86,7 +86,7 @@ public function getUpdateForm(string $profile, int $id): EntityForm {
     $result = $this->client->executeV4($this->getRemoteEntityName(), 'getUpdateForm', [
       'profile' => $profile,
       'id' => $id,
-      'remoteContactId' => $this->remoteContactIdProvider->getRemoteContactId(),
+      'remoteContactId' => $this->remoteContactIdProvider->getRemoteContactIdOrNull(),
     ]);
 
     return EntityForm::fromApiResultValue($result['values']);
@@ -100,7 +100,7 @@ public function submitUpdateForm(string $profile, int $id, array $data): FormSub
       'profile' => $profile,
       'id' => $id,
       'data' => $data,
-      'remoteContactId' => $this->remoteContactIdProvider->getRemoteContactId(),
+      'remoteContactId' => $this->remoteContactIdProvider->getRemoteContactIdOrNull(),
     ]);
 
     return FormSubmitResponse::fromApiResultValue($result['values']);
@@ -114,7 +114,7 @@ public function validateUpdateForm(string $profile, int $id, array $data): FormV
       'profile' => $profile,
       'id' => $id,
       'data' => $data,
-      'remoteContactId' => $this->remoteContactIdProvider->getRemoteContactId(),
+      'remoteContactId' => $this->remoteContactIdProvider->getRemoteContactIdOrNull(),
     ]);
 
     return FormValidationResponse::fromApiResultValue($result['values']);