diff --git a/embargo.services.yml b/embargo.services.yml
index fff9bb0..d5a6f3c 100644
--- a/embargo.services.yml
+++ b/embargo.services.yml
@@ -18,11 +18,12 @@ services:
       - '@entity_type.manager'
       - '@datetime.time'
       - '@date.formatter'
+      - '@event_dispatcher'
   embargo.route_subscriber:
     class: Drupal\embargo\Routing\EmbargoRouteSubscriber
     arguments: ['@entity_type.manager']
     tags:
-      - { name: event_subscriber }
+      - { name: 'event_subscriber' }
   embargo.ip_range_redirect:
     class: '\Drupal\embargo\EventSubscriber\IpRangeRedirect'
     arguments:
@@ -56,4 +57,9 @@ services:
       - '@request_stack'
       - '@entity_type.manager'
     tags:
-      - { name: cache.context }
+      - { name: 'cache.context' }
+  embargo.tagging_event_subscriber:
+    class: Drupal\embargo\EventSubscriber\TaggingEventSubscriber
+    tags:
+      - { name: 'event_subscriber' }
+
diff --git a/src/Access/QueryTagger.php b/src/Access/QueryTagger.php
index 202c158..c5b0189 100644
--- a/src/Access/QueryTagger.php
+++ b/src/Access/QueryTagger.php
@@ -13,6 +13,7 @@
 use Drupal\islandora_hierarchical_access\Access\QueryConjunctionTrait;
 use Drupal\islandora_hierarchical_access\TaggedTargetsTrait;
 use Symfony\Component\HttpFoundation\RequestStack;
+use Symfony\Contracts\EventDispatcher\EventDispatcherInterface;
 
 /**
  * Handles tagging entity queries with access restrictions for embargoes.
@@ -32,7 +33,8 @@ public function __construct(
     Connection $database,
     EntityTypeManagerInterface $entity_type_manager,
     TimeInterface $time,
-    DateFormatterInterface $date_formatter
+    DateFormatterInterface $date_formatter,
+    EventDispatcherInterface $event_dispatcher,
   ) {
     $this->user = $user;
     $this->currentIp = $request_stack->getCurrentRequest()->getClientIp();
@@ -40,6 +42,7 @@ public function __construct(
     $this->entityTypeManager = $entity_type_manager;
     $this->time = $time;
     $this->dateFormatter = $date_formatter;
+    $this->setEventDispatcher($event_dispatcher);
   }
 
   /**
diff --git a/src/EmbargoExistenceQueryTrait.php b/src/EmbargoExistenceQueryTrait.php
index cf7f84e..18db51b 100644
--- a/src/EmbargoExistenceQueryTrait.php
+++ b/src/EmbargoExistenceQueryTrait.php
@@ -10,6 +10,9 @@
 use Drupal\Core\Entity\EntityTypeManagerInterface;
 use Drupal\Core\Session\AccountProxyInterface;
 use Drupal\datetime\Plugin\Field\FieldType\DateTimeItemInterface;
+use Drupal\embargo\Event\TagExclusionEvent;
+use Drupal\embargo\Event\TagInclusionEvent;
+use Symfony\Contracts\EventDispatcher\EventDispatcherInterface;
 
 /**
  * Helper trait; facilitate filtering of embargoed entities.
@@ -58,6 +61,13 @@ trait EmbargoExistenceQueryTrait {
    */
   protected DateFormatterInterface $dateFormatter;
 
+  /**
+   * The event dispatcher service.
+   *
+   * @var \Symfony\Contracts\EventDispatcher\EventDispatcherInterface
+   */
+  protected EventDispatcherInterface $eventDispatcher;
+
   /**
    * Helper; apply existence checks to a node(-like) table.
    *
@@ -80,6 +90,30 @@ protected function applyExistenceQuery(
     );
   }
 
+  /**
+   * Set the event dispatcher service.
+   *
+   * @param \Symfony\Contracts\EventDispatcher\EventDispatcherInterface $event_dispatcher
+   *   The event dispatcher service to set.
+   *
+   * @return \Drupal\embargo\EmbargoExistenceQueryTrait|\Drupal\embargo\Access\QueryTagger|\Drupal\embargo\EventSubscriber\IslandoraHierarchicalAccessEventSubscriber
+   *   The current instance; fluent interface.
+   */
+  protected function setEventDispatcher(EventDispatcherInterface $event_dispatcher) : self {
+    $this->eventDispatcher = $event_dispatcher;
+    return $this;
+  }
+
+  /**
+   * Get the event dispatcher service.
+   *
+   * @return \Symfony\Contracts\EventDispatcher\EventDispatcherInterface
+   *   The event dispatcher service.
+   */
+  protected function getEventDispatch() : EventDispatcherInterface {
+    return $this->eventDispatcher ?? \Drupal::service('event_dispatcher');
+  }
+
   /**
    * Build out condition for matching embargo entities.
    *
@@ -90,17 +124,9 @@ protected function applyExistenceQuery(
    *   The condition to attach.
    */
   protected function buildInclusionBaseCondition(SelectInterface $query) : ConditionInterface {
-    $condition = $query->orConditionGroup();
+    $dispatched_event = $this->getEventDispatch()->dispatch(new TagInclusionEvent($query));
 
-    $embargo_alias = $query->getMetaData('embargo_alias');
-    $target_aliases = $query->getMetaData('embargo_target_aliases');
-
-    $condition->where(strtr('!field IN (!targets)', [
-      '!field' => "{$embargo_alias}.embargoed_node",
-      '!targets' => implode(', ', $target_aliases),
-    ]));
-
-    return $condition;
+    return $dispatched_event->getCondition();
   }
 
   /**
@@ -113,14 +139,9 @@ protected function buildInclusionBaseCondition(SelectInterface $query) : Conditi
    *   The condition to attach.
    */
   protected function buildExclusionBaseCondition(SelectInterface $query) : ConditionInterface {
-    $condition = $query->orConditionGroup();
-
-    $embargo_alias = $query->getMetaData('embargo_alias');
-    $unexpired_alias = $query->getMetaData('embargo_unexpired_alias');
-
-    $condition->where("{$unexpired_alias}.embargoed_node = {$embargo_alias}.embargoed_node");
+    $dispatched_event = $this->getEventDispatch()->dispatch(new TagExclusionEvent($query));
 
-    return $condition;
+    return $dispatched_event->getCondition();
   }
 
   /**
diff --git a/src/Event/AbstractTagEvent.php b/src/Event/AbstractTagEvent.php
new file mode 100644
index 0000000..220c62c
--- /dev/null
+++ b/src/Event/AbstractTagEvent.php
@@ -0,0 +1,70 @@
+<?php
+
+namespace Drupal\embargo\Event;
+
+use Drupal\Core\Database\Query\ConditionInterface;
+use Drupal\Core\Database\Query\SelectInterface;
+use Symfony\Contracts\EventDispatcher\Event;
+
+/**
+ * Abstract base tag event class.
+ */
+abstract class AbstractTagEvent extends Event {
+
+  /**
+   * The build condition.
+   *
+   * @var \Drupal\Core\Database\Query\ConditionInterface
+   */
+  protected ConditionInterface $condition;
+
+  /**
+   * Constructor.
+   */
+  public function __construct(
+    protected SelectInterface $query,
+  ) {
+    $this->condition = $this->query->orConditionGroup();
+  }
+
+  /**
+   * Get the query upon which to act.
+   *
+   * @return \Drupal\Core\Database\Query\SelectInterface
+   *   The query upon which we are to act.
+   */
+  public function getQuery() : SelectInterface {
+    return $this->query;
+  }
+
+  /**
+   * Get the current condition.
+   *
+   * @return \Drupal\Core\Database\Query\ConditionInterface
+   *   The current condition.
+   */
+  public function getCondition() : ConditionInterface {
+    return $this->condition;
+  }
+
+  /**
+   * Get the base "embargo" table alias.
+   *
+   * @return string
+   *   The base "embargo" alias, as used in the query.
+   */
+  public function getEmbargoAlias() : string {
+    return $this->query->getMetaData('embargo_alias');
+  }
+
+  /**
+   * Get the base query columns representing node IDs to find embargoes.
+   *
+   * @return string[]
+   *   The column aliases representing node IDs.
+   */
+  public function getTargetAliases() : array {
+    return $this->query->getMetaData('embargo_target_aliases');
+  }
+
+}
diff --git a/src/Event/EmbargoEvents.php b/src/Event/EmbargoEvents.php
new file mode 100644
index 0000000..effceb4
--- /dev/null
+++ b/src/Event/EmbargoEvents.php
@@ -0,0 +1,14 @@
+<?php
+
+namespace Drupal\embargo\Event;
+
+/**
+ * Enumerate our event types.
+ */
+final class EmbargoEvents {
+
+  const TAG_INCLUSION = TagInclusionEvent::class;
+
+  const TAG_EXCLUSION = TagExclusionEvent::class;
+
+}
diff --git a/src/Event/TagExclusionEvent.php b/src/Event/TagExclusionEvent.php
new file mode 100644
index 0000000..962b9ca
--- /dev/null
+++ b/src/Event/TagExclusionEvent.php
@@ -0,0 +1,20 @@
+<?php
+
+namespace Drupal\embargo\Event;
+
+/**
+ * Query tagging exclusion event.
+ */
+class TagExclusionEvent extends AbstractTagEvent {
+
+  /**
+   * Get the "unexpired" embargo alias.
+   *
+   * @return string
+   *   The table alias.
+   */
+  public function getUnexpiredAlias() : string {
+    return $this->query->getMetaData('embargo_unexpired_alias');
+  }
+
+}
diff --git a/src/Event/TagInclusionEvent.php b/src/Event/TagInclusionEvent.php
new file mode 100644
index 0000000..42937a7
--- /dev/null
+++ b/src/Event/TagInclusionEvent.php
@@ -0,0 +1,10 @@
+<?php
+
+namespace Drupal\embargo\Event;
+
+/**
+ * Query tagging inclusion event.
+ */
+class TagInclusionEvent extends AbstractTagEvent {
+
+}
diff --git a/src/EventSubscriber/IslandoraHierarchicalAccessEventSubscriber.php b/src/EventSubscriber/IslandoraHierarchicalAccessEventSubscriber.php
index bad9e35..56010e3 100644
--- a/src/EventSubscriber/IslandoraHierarchicalAccessEventSubscriber.php
+++ b/src/EventSubscriber/IslandoraHierarchicalAccessEventSubscriber.php
@@ -42,14 +42,15 @@ public function __construct(
    * {@inheritDoc}
    */
   public static function create(ContainerInterface $container) : self {
-    return new static(
+    return (new static(
       $container->get('current_user'),
       $container->get('request_stack'),
       $container->get('database'),
       $container->get('entity_type.manager'),
       $container->get('datetime.time'),
       $container->get('date.formatter'),
-    );
+    ))
+      ->setEventDispatcher($container->get('event_dispatcher'));
   }
 
   /**
diff --git a/src/EventSubscriber/TaggingEventSubscriber.php b/src/EventSubscriber/TaggingEventSubscriber.php
new file mode 100644
index 0000000..8d86a1e
--- /dev/null
+++ b/src/EventSubscriber/TaggingEventSubscriber.php
@@ -0,0 +1,48 @@
+<?php
+
+namespace Drupal\embargo\EventSubscriber;
+
+use Drupal\embargo\Event\EmbargoEvents;
+use Drupal\embargo\Event\TagExclusionEvent;
+use Drupal\embargo\Event\TagInclusionEvent;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+
+/**
+ * Query tagging event subscriber.
+ */
+class TaggingEventSubscriber implements EventSubscriberInterface {
+
+  /**
+   * {@inheritDoc}
+   */
+  public static function getSubscribedEvents() : array {
+    return [
+      EmbargoEvents::TAG_INCLUSION => 'inclusion',
+      EmbargoEvents::TAG_EXCLUSION => 'exclusion',
+    ];
+  }
+
+  /**
+   * Event handler; tagging inclusion event.
+   *
+   * @param \Drupal\embargo\Event\TagInclusionEvent $event
+   *   The event being handled.
+   */
+  public function inclusion(TagInclusionEvent $event) : void {
+    $event->getCondition()->where(strtr('!field IN (!targets)', [
+      '!field' => "{$event->getEmbargoAlias()}.embargoed_node",
+      '!targets' => implode(', ', $event->getTargetAliases()),
+    ]));
+  }
+
+  /**
+   * Event handler; tagging exclusion event.
+   *
+   * @param \Drupal\embargo\Event\TagExclusionEvent $event
+   *   The event being handled.
+   */
+  public function exclusion(TagExclusionEvent $event) : void {
+    $event->getCondition()->where("{$event->getUnexpiredAlias()}.embargoed_node = {$event->getEmbargoAlias()}.embargoed_node");
+  }
+
+}