diff --git a/mod/forum/discuss.php b/mod/forum/discuss.php
index 382b7be8a9962..43d58e3302535 100644
--- a/mod/forum/discuss.php
+++ b/mod/forum/discuss.php
@@ -64,14 +64,6 @@
         rss_add_http_header($modcontext, 'mod_forum', $forum, $rsstitle);
     }
 
-    if ($forum->type == 'news') {
-        if (!($USER->id == $discussion->userid || (($discussion->timestart == 0
-            || $discussion->timestart <= time())
-            && ($discussion->timeend == 0 || $discussion->timeend > time())))) {
-            print_error('invaliddiscussionid', 'forum', "$CFG->wwwroot/mod/forum/view.php?f=$forum->id");
-        }
-    }
-
 /// move discussion if requested
     if ($move > 0 and confirm_sesskey()) {
         $return = $CFG->wwwroot.'/mod/forum/discuss.php?d='.$discussion->id;
@@ -140,9 +132,8 @@
         print_error("notexists", 'forum', "$CFG->wwwroot/mod/forum/view.php?f=$forum->id");
     }
 
-
-    if (!forum_user_can_view_post($post, $course, $cm, $forum, $discussion)) {
-        print_error('nopermissiontoview', 'forum', "$CFG->wwwroot/mod/forum/view.php?id=$forum->id");
+    if (!forum_user_can_see_post($forum, $discussion, $post, null, $cm)) {
+        print_error('noviewdiscussionspermission', 'forum', "$CFG->wwwroot/mod/forum/view.php?id=$forum->id");
     }
 
     if ($mark == 'read' or $mark == 'unread') {
diff --git a/mod/forum/lang/en/forum.php b/mod/forum/lang/en/forum.php
index de2c49e8d63db..5772cf34e200d 100644
--- a/mod/forum/lang/en/forum.php
+++ b/mod/forum/lang/en/forum.php
@@ -158,7 +158,7 @@
 $string['forum:allowforcesubscribe'] = 'Allow force subscribe';
 $string['forumauthorhidden'] = 'Author (hidden)';
 $string['forumblockingalmosttoomanyposts'] = 'You are approaching the posting threshold. You have posted {$a->numposts} times in the last {$a->blockperiod} and the limit is {$a->blockafter} posts.';
-$string['forumbodyhidden'] = 'This post cannot be viewed by you, probably because you have not posted in the discussion or the maximum editing time hasn\'t passed yet.';
+$string['forumbodyhidden'] = 'This post cannot be viewed by you, probably because you have not posted in the discussion, the maximum editing time hasn\'t passed yet, the discussion has not started or the discussion has expired.';
 $string['forum:createattachment'] = 'Create attachments';
 $string['forum:deleteanypost'] = 'Delete any posts (anytime)';
 $string['forum:deleteownpost'] = 'Delete own posts (within deadline)';
diff --git a/mod/forum/lib.php b/mod/forum/lib.php
index a7065719a7823..eca7c98e7ea7e 100644
--- a/mod/forum/lib.php
+++ b/mod/forum/lib.php
@@ -5169,7 +5169,6 @@ function forum_user_can_post($forum, $discussion, $user=NULL, $cm=NULL, $course=
     }
 }
 
-
 /**
  * checks to see if a user can view a particular post
  *
@@ -5207,6 +5206,51 @@ function forum_user_can_view_post($post, $course, $cm, $forum, $discussion, $use
     return true;
 }
 
+/**
+ * Check to ensure a user can view a timed discussion.
+ *
+ * @param object $discussion
+ * @param object $user
+ * @param object $context
+ * @return boolean returns true if they can view post, false otherwise
+ */
+function forum_user_can_see_timed_discussion($discussion, $user, $context) {
+    global $CFG;
+
+    // Check that the user can view a discussion that is normally hidden due to access times.
+    if (!empty($CFG->forum_enabletimedposts)) {
+        $time = time();
+        if (($discussion->timestart != 0 && $discussion->timestart > $time)
+            || ($discussion->timeend != 0 && $discussion->timeend < $time)) {
+            if (!has_capability('mod/forum:viewhiddentimedposts', $context, $user->id)) {
+                return false;
+            }
+        }
+    }
+
+    return true;
+}
+
+/**
+ * Check to ensure a user can view a group discussion.
+ *
+ * @param object $discussion
+ * @param object $cm
+ * @param object $context
+ * @return boolean returns true if they can view post, false otherwise
+ */
+function forum_user_can_see_group_discussion($discussion, $cm, $context) {
+
+    // If it's a grouped discussion, make sure the user is a member.
+    if ($discussion->groupid > 0) {
+        $groupmode = groups_get_activity_groupmode($cm);
+        if ($groupmode == SEPARATEGROUPS) {
+            return groups_is_member($discussion->groupid) || has_capability('moodle/site:accessallgroups', $context);
+        }
+    }
+
+    return true;
+}
 
 /**
  * @global object
@@ -5238,11 +5282,22 @@ function forum_user_can_see_discussion($forum, $discussion, $context, $user=NULL
             return false;
         }
     }
+    if (!$cm = get_coursemodule_from_instance('forum', $forum->id, $forum->course)) {
+        print_error('invalidcoursemodule');
+    }
 
     if (!has_capability('mod/forum:viewdiscussion', $context)) {
         return false;
     }
 
+    if (!forum_user_can_see_timed_discussion($discussion, $user, $context)) {
+        return false;
+    }
+
+    if (!forum_user_can_see_group_discussion($discussion, $cm, $context)) {
+        return false;
+    }
+
     if ($forum->type == 'qanda' &&
             !forum_user_has_posted($forum->id, $discussion->id, $user->id) &&
             !has_capability('mod/forum:viewqandawithoutposting', $context)) {
@@ -5265,6 +5320,9 @@ function forum_user_can_see_discussion($forum, $discussion, $context, $user=NULL
 function forum_user_can_see_post($forum, $discussion, $post, $user=NULL, $cm=NULL) {
     global $CFG, $USER, $DB;
 
+    // Context used throughout function.
+    $modcontext = get_context_instance(CONTEXT_MODULE, $cm->id);
+
     // retrieve objects (yuk)
     if (is_numeric($forum)) {
         debugging('missing full forum', DEBUG_DEVELOPER);
@@ -5285,6 +5343,7 @@ function forum_user_can_see_post($forum, $discussion, $post, $user=NULL, $cm=NUL
             return false;
         }
     }
+
     if (!isset($post->id) && isset($post->parent)) {
         $post->id = $post->parent;
     }
@@ -5300,7 +5359,7 @@ function forum_user_can_see_post($forum, $discussion, $post, $user=NULL, $cm=NUL
         $user = $USER;
     }
 
-    $canviewdiscussion = !empty($cm->cache->caps['mod/forum:viewdiscussion']) || has_capability('mod/forum:viewdiscussion', get_context_instance(CONTEXT_MODULE, $cm->id), $user->id);
+    $canviewdiscussion = !empty($cm->cache->caps['mod/forum:viewdiscussion']) || has_capability('mod/forum:viewdiscussion', $modcontext, $user->id);
     if (!$canviewdiscussion && !has_all_capabilities(array('moodle/user:viewdetails', 'moodle/user:readuserposts'), get_context_instance(CONTEXT_USER, $post->userid))) {
         return false;
     }
@@ -5315,9 +5374,16 @@ function forum_user_can_see_post($forum, $discussion, $post, $user=NULL, $cm=NUL
         }
     }
 
+    if (!forum_user_can_see_timed_discussion($discussion, $user, $modcontext)) {
+        return false;
+    }
+
+    if (!forum_user_can_see_group_discussion($discussion, $cm, $modcontext)) {
+        return false;
+    }
+
     if ($forum->type == 'qanda') {
         $firstpost = forum_get_firstpost_from_discussion($discussion->id);
-        $modcontext = get_context_instance(CONTEXT_MODULE, $cm->id);
         $userfirstpost = forum_get_user_posted_time($discussion->id, $user->id);
 
         return (($userfirstpost !== false && (time() - $userfirstpost >= $CFG->maxeditingtime)) ||