diff --git a/app/models/user_identifier.rb b/app/models/user_identifier.rb
index 02a8cb9..5a1f5ad 100644
--- a/app/models/user_identifier.rb
+++ b/app/models/user_identifier.rb
@@ -35,10 +35,8 @@
 
   validates :user, presence: true
 
-  validates :identifier_scheme, presence: true
-
-  validates :identifier_scheme_id, uniqueness: { scope: :user_id,
-                                                 message: UNIQUENESS_MESSAGE }
+  validates :identifier_scheme, presence: { message: PRESENCE_MESSAGE }
 
   validates :identifier, presence: { message: PRESENCE_MESSAGE }
+
 end
diff --git a/spec/models/user_identifier_spec.rb b/spec/models/user_identifier_spec.rb
index 253d0d7..f49f212 100644
--- a/spec/models/user_identifier_spec.rb
+++ b/spec/models/user_identifier_spec.rb
@@ -3,14 +3,9 @@
 RSpec.describe UserIdentifier, type: :model do
   context "validations" do
     it { is_expected.to validate_presence_of(:identifier) }
+
     it { is_expected.to validate_presence_of(:user) }
-    it "validates uniqueness of identifier_scheme_id" do
-      subject.identifier_scheme = create(:identifier_scheme)
-      expect(subject).to validate_uniqueness_of(:identifier_scheme_id)
-                           .case_insensitive
-                           .scoped_to(:user_id)
-                           .with_message("must be unique")
-    end
+
     it { is_expected.to validate_presence_of(:identifier_scheme) }
   end
 end