diff --git a/app/models/terms_of_service.rb b/app/models/terms_of_service.rb
index f29094036..93fe4af9c 100644
--- a/app/models/terms_of_service.rb
+++ b/app/models/terms_of_service.rb
@@ -20,6 +20,7 @@ class TermsOfService < ApplicationRecord
 
   validates :text, presence: true
   validates :changelog, :effective_date, presence: true, if: -> { published? }
+  validates :effective_date, uniqueness: true
 
   validate :effective_date_cannot_be_in_the_past