diff --git a/app/assets/javascripts/admin/orders/controllers/orders_controller.js.coffee b/app/assets/javascripts/admin/orders/controllers/orders_controller.js.coffee
index 338ec21f0b..ad5bfff97d 100644
--- a/app/assets/javascripts/admin/orders/controllers/orders_controller.js.coffee
+++ b/app/assets/javascripts/admin/orders/controllers/orders_controller.js.coffee
@@ -25,8 +25,9 @@ angular.module("admin.orders").controller "ordersCtrl", ($scope, RequestMonitor,
       'q[email_cont]': $scope['q']['email_cont'],
       'q[bill_address_firstname_start]': $scope['q']['bill_address_firstname_start'],
       'q[bill_address_lastname_start]': $scope['q']['bill_address_lastname_start'],
-      'q[completed_at_not_null]': $scope['q']['completed_at_not_null'],
-      'q[inventory_units_shipment_id_null]': $scope['q']['inventory_units_shipment_id_null'],
+      # Set default checkbox values to null. See: https://github.com/openfoodfoundation/openfoodnetwork/pull/3076#issuecomment-440010498
+      'q[completed_at_not_null]': $scope['q']['completed_at_not_null'] || null,
+      'q[inventory_units_shipment_id_null]': $scope['q']['inventory_units_shipment_id_null'] || null,
       'q[distributor_id_in]': $scope['q']['distributor_id_in'],
       'q[order_cycle_id_in]': $scope['q']['order_cycle_id_in'],
       'q[order_cycle_id_in]': $scope['q']['order_cycle_id_in'],
diff --git a/app/services/search_orders.rb b/app/services/search_orders.rb
index 127a53625e..c1120ffb19 100644
--- a/app/services/search_orders.rb
+++ b/app/services/search_orders.rb
@@ -26,11 +26,11 @@ class SearchOrders
     @search = OpenFoodNetwork::Permissions.new(current_user).editable_orders.ransack(params[:q])
 
     return paginated_results if using_pagination?
-    @search.result
+    @search.result(distinct: true)
   end
 
   def paginated_results
-    @search.result
+    @search.result(distinct: true)
       .page(params[:page])
       .per(params[:per_page])
   end
diff --git a/spec/controllers/api/orders_controller_spec.rb b/spec/controllers/api/orders_controller_spec.rb
index 9bcdbeb7ad..760094570d 100644
--- a/spec/controllers/api/orders_controller_spec.rb
+++ b/spec/controllers/api/orders_controller_spec.rb
@@ -24,6 +24,8 @@ module Api
         create(:order, order_cycle: order_cycle, state: 'complete', completed_at: Time.zone.now,
                        distributor: distributor, billing_address: create(:address) )
       end
+      let!(:order4) { create(:completed_order_with_fees) }
+      let!(:order5) { create(:order, state: 'cart', completed_at: nil) }
       let!(:line_item1) do
         create(:line_item, order: order1,
                            product: create(:product, supplier: supplier))
@@ -119,6 +121,24 @@ module Api
         end
       end
 
+      context 'using search filters' do
+        before do
+          allow(controller).to receive(:spree_current_user) { admin_user }
+        end
+
+        it 'can show only completed orders' do
+          get :index, format: :json, q: { completed_at_not_null: true, s: 'created_at desc' }
+
+          expect(json_response['orders']).to eq serialized_orders([order4, order3, order2, order1])
+        end
+
+        it 'can show only unfulfilled orders' do
+          get :index, format: :json, q: { inventory_units_shipment_id_null: true, s: 'created_at desc' }
+
+          expect(json_response['orders']).to eq serialized_orders([order3, order2, order1])
+        end
+      end
+
       context 'with pagination' do
         before do
           allow(controller).to receive(:spree_current_user) { distributor.owner }
@@ -128,7 +148,7 @@ module Api
           get :index, per_page: 15, page: 1
 
           pagination_data = {
-            'results' => 2,
+            'results' => 3,
             'pages' => 1,
             'page' => 1,
             'per_page' => 15
@@ -141,6 +161,16 @@ module Api
 
     private
 
+    def serialized_orders(orders)
+      serialized_orders = ActiveModel::ArraySerializer.new(
+        orders,
+        each_serializer: Api::Admin::OrderSerializer,
+        root: false
+      )
+
+      JSON.parse(serialized_orders.to_json)
+    end
+
     def returns_orders(response)
       keys = response['orders'].first.keys.map(&:to_sym)
       expect(order_attributes.all?{ |attr| keys.include? attr }).to be_truthy