diff --git a/ietf/meeting/tests_js.py b/ietf/meeting/tests_js.py
index 78025d7a7..228fa21f7 100644
--- a/ietf/meeting/tests_js.py
+++ b/ietf/meeting/tests_js.py
@@ -26,7 +26,7 @@ from ietf.person.models import Person
 from ietf.group.models import Group
 from ietf.group.factories import GroupFactory
 from ietf.meeting.factories import ( MeetingFactory, RoomFactory, SessionFactory, TimeSlotFactory,
-                                     ProceedingsMaterialFactory )
+                                     ProceedingsMaterialFactory, ScheduleFactory, ConstraintFactory )
 from ietf.meeting.test_data import make_meeting_test_data, make_interim_meeting
 from ietf.meeting.models import (Schedule, SchedTimeSessAssignment, Session,
                                  Room, TimeSlot, Constraint, ConstraintName,
@@ -794,6 +794,56 @@ class EditMeetingScheduleTests(IetfSeleniumTestCase):
         self.assertGreater(drop_target.size['width'], 0,
                            'Drop target for unassigned sessions collapsed to 0 width')
 
+    def test_session_constraint_hints(self):
+        """Selecting a session should mark conflicting sessions
+
+        To test for recurrence of https://trac.ietf.org/trac/ietfdb/ticket/3327 need to have some constraints that
+        do not conflict. Testing with only violated constraints does not exercise the code adequately.
+        """
+        meeting = MeetingFactory(type_id='ietf', date=datetime.date.today(), populate_schedule=False)
+        TimeSlotFactory.create_batch(5, meeting=meeting)
+        schedule = ScheduleFactory(meeting=meeting)
+        sessions = SessionFactory.create_batch(5, meeting=meeting, add_to_schedule=False)
+        groups = [s.group for s in sessions]
+
+        # Now set up constraints
+        # Get an arbitrary enabled group conflict ConstraintName
+        constraint_names = meeting.enabled_constraint_names().filter(is_group_conflict=True)
+        self.assertGreaterEqual(len(constraint_names), 2, 'Not enough constraint names enabled to perform test')
+
+        # one-way conflict from group 0 to 1
+        ConstraintFactory(meeting=meeting, name=constraint_names[0], source=groups[0], target=groups[1], person=None)
+
+        # one-way conflict from group 2 to 0
+        ConstraintFactory(meeting=meeting, name=constraint_names[0], source=groups[2], target=groups[0], person=None)
+
+        # two-way conflict between groups 0 and 3
+        ConstraintFactory(meeting=meeting, name=constraint_names[0], source=groups[0], target=groups[3], person=None)
+        ConstraintFactory(meeting=meeting, name=constraint_names[0], source=groups[3], target=groups[0], person=None)
+
+        # constraints that are not active when selecting sessions[0]
+        ConstraintFactory(meeting=meeting, name=constraint_names[1], source=groups[1], target=groups[2], person=None)
+        ConstraintFactory(meeting=meeting, name=constraint_names[1], source=groups[3], target=groups[4], person=None)
+
+        url = self.absreverse('ietf.meeting.views.edit_meeting_schedule',
+                              kwargs=dict(num=meeting.number, owner=schedule.owner.email(), name=schedule.name))
+        self.login(schedule.owner.user.username)
+        self.driver.get(url)
+        session_elements = [self.driver.find_element_by_css_selector(f'#session{sess.pk}') for sess in sessions]
+        session_elements[0].click()
+
+        # All conflicting sessions should be flagged with the would-violate-hint class.
+        self.assertIn('would-violate-hint', session_elements[1].get_attribute('class'),
+                      'Constraint violation should be indicated on conflicting session')
+        self.assertIn('would-violate-hint', session_elements[2].get_attribute('class'),
+                      'Constraint violation should be indicated on conflicting session')
+        self.assertIn('would-violate-hint', session_elements[3].get_attribute('class'),
+                      'Constraint violation should be indicated on conflicting session')
+
+        # And the non-conflicting session should not be flagged
+        self.assertNotIn('would-violate-hint', session_elements[4].get_attribute('class'),
+                         'Constraint violation should not be indicated on non-conflicting session')
+
 @ifSeleniumEnabled
 @skipIf(django.VERSION[0]==2, "Skipping test with race conditions under Django 2")
 class ScheduleEditTests(IetfSeleniumTestCase):
diff --git a/ietf/static/ietf/js/edit-meeting-schedule.js b/ietf/static/ietf/js/edit-meeting-schedule.js
index 40d90a9cb..b4aa3e365 100644
--- a/ietf/static/ietf/js/edit-meeting-schedule.js
+++ b/ietf/static/ietf/js/edit-meeting-schedule.js
@@ -26,6 +26,7 @@ jQuery(document).ready(function () {
     }
 
     let sessions = content.find(".session").not(".readonly");
+    let sessionConstraints = sessions.find('.constraints > span');
     let timeslots = content.find(".timeslot");
     let timeslotLabels = content.find(".time-label");
     let swapDaysButtons = content.find('.swap-days');
@@ -154,25 +155,26 @@ jQuery(document).ready(function () {
         timeslotLabels.removeClass("would-violate-hint");
     }
 
+    /**
+     * Remove all would-violate-hint classes on sessions and their formatted constraints
+     */
+    function resetSessionsWouldViolate() {
+        sessions.removeClass("would-violate-hint");
+        sessionConstraints.removeClass("would-violate-hint");
+    }
+
     function showConstraintHints(selectedSession) {
         let sessionId = selectedSession ? selectedSession.id.slice("session".length) : null;
         // hints on the sessions
-        sessions.find(".constraints > span").each(function () {
-            let wouldViolate = false;
-            let applyChange = true;
-            if (sessionId) {
+        resetSessionsWouldViolate();
+        if (sessionId) {
+            sessionConstraints.each(function () {
                 let sessionIds = this.dataset.sessions;
-                if (!sessionIds) {
-                    applyChange = false;
-                } else {
-                    wouldViolate = sessionIds.split(",").indexOf(sessionId) !== -1;
+                if (sessionIds && (sessionIds.split(",").indexOf(sessionId) !== -1)) {
+                    setSessionWouldViolate(this, true);
                 }
-            }
-
-            if (applyChange) {
-                setSessionWouldViolate(this, wouldViolate);
-            }
-        });
+            });
+        }
 
         // hints on timeslots
         resetTimeslotsWouldViolate();