diff --git a/app/controllers/admin/accompagnateurs_controller.rb b/app/controllers/admin/accompagnateurs_controller.rb
index 1f7ca7c7f..f695dca07 100644
--- a/app/controllers/admin/accompagnateurs_controller.rb
+++ b/app/controllers/admin/accompagnateurs_controller.rb
@@ -4,6 +4,9 @@ class Admin::AccompagnateursController < AdminController
 
   before_action :retrieve_procedure
 
+  ASSIGN = 'assign'
+  NOT_ASSIGN = 'not_assign'
+
   def show
     assign_scope = @procedure.gestionnaires
 
@@ -46,11 +49,21 @@ class Admin::AccompagnateursController < AdminController
     procedure = Procedure.find(params[:procedure_id])
     to = params[:to]
 
-    accompagnateur_service = AccompagnateurService.new gestionnaire, procedure, to
+    case to
+    when ASSIGN
+      if gestionnaire.assign_to_procedure(procedure)
+        flash.notice = "L'accompagnateur a bien été affecté"
+      else
+        flash.alert = "L'accompagnateur a déjà été affecté"
+      end
+    when NOT_ASSIGN
+      if gestionnaire.remove_from_procedure(procedure)
+        flash.notice = "L'accompagnateur a bien été désaffecté"
+      else
+        flash.alert = "L'accompagnateur a déjà été désaffecté"
+      end
+    end
 
-    accompagnateur_service.change_assignement!
-
-    flash.notice = "Assignement effectué"
     redirect_to admin_procedure_accompagnateurs_path, procedure_id: params[:procedure_id]
   end
 end
diff --git a/app/controllers/new_gestionnaire/procedures_controller.rb b/app/controllers/new_gestionnaire/procedures_controller.rb
index 0131bcb61..7b4d958a6 100644
--- a/app/controllers/new_gestionnaire/procedures_controller.rb
+++ b/app/controllers/new_gestionnaire/procedures_controller.rb
@@ -6,7 +6,7 @@ module NewGestionnaire
     ITEMS_PER_PAGE = 25
 
     def index
-      @procedures = current_gestionnaire.procedures.order(archived_at: :desc, published_at: :desc)
+      @procedures = current_gestionnaire.visible_procedures.order(archived_at: :desc, published_at: :desc)
 
       dossiers = current_gestionnaire.dossiers
       @dossiers_count_per_procedure = dossiers.all_state.group(:procedure_id).reorder(nil).count
@@ -202,7 +202,7 @@ module NewGestionnaire
     end
 
     def redirect_to_avis_if_needed
-      if current_gestionnaire.procedures.count == 0 && current_gestionnaire.avis.count > 0
+      if current_gestionnaire.visible_procedures.count == 0 && current_gestionnaire.avis.count > 0
         redirect_to gestionnaire_avis_index_path
       end
     end
diff --git a/app/models/gestionnaire.rb b/app/models/gestionnaire.rb
index 9a9a01b0b..4b4a98aa2 100644
--- a/app/models/gestionnaire.rb
+++ b/app/models/gestionnaire.rb
@@ -5,7 +5,7 @@ class Gestionnaire < ActiveRecord::Base
   has_and_belongs_to_many :administrateurs
 
   has_many :assign_to, dependent: :destroy
-  has_many :procedures, -> { publiees_ou_archivees }, through: :assign_to
+  has_many :procedures, through: :assign_to
   has_many :dossiers, -> { state_not_brouillon }, through: :procedures
   has_many :follows
   has_many :followed_dossiers, through: :follows, source: :dossier
@@ -14,6 +14,10 @@ class Gestionnaire < ActiveRecord::Base
 
   include CredentialsSyncableConcern
 
+  def visible_procedures
+    procedures.publiees_ou_archivees
+  end
+
   def procedure_filter
     procedure_id = self[:procedure_filter]
     if procedures.find_by(id: procedure_id).present?
@@ -47,6 +51,19 @@ class Gestionnaire < ActiveRecord::Base
     procedures.find_by(id: procedure_id).present?
   end
 
+  def assign_to_procedure(procedure)
+    begin
+      procedures << procedure
+      true
+    rescue ActiveRecord::RecordNotUnique
+      false
+    end
+  end
+
+  def remove_from_procedure(procedure)
+    !!(procedure.in?(procedures) && procedures.destroy(procedure))
+  end
+
   def last_week_overview
     start_date = DateTime.now.beginning_of_week
 
diff --git a/app/services/accompagnateur_service.rb b/app/services/accompagnateur_service.rb
deleted file mode 100644
index 2546506a9..000000000
--- a/app/services/accompagnateur_service.rb
+++ /dev/null
@@ -1,19 +0,0 @@
-class AccompagnateurService
-  ASSIGN = 'assign'
-  NOT_ASSIGN = 'not_assign'
-
-  def initialize accompagnateur, procedure, to
-    @accompagnateur = accompagnateur
-    @procedure = procedure
-    @to = to
-  end
-
-  def change_assignement!
-    case @to
-    when ASSIGN
-      AssignTo.create(gestionnaire: @accompagnateur, procedure: @procedure)
-    when NOT_ASSIGN
-      AssignTo.where(gestionnaire: @accompagnateur, procedure: @procedure).delete_all
-    end
-  end
-end
diff --git a/app/views/admin/accompagnateurs/_list_assign.html.haml b/app/views/admin/accompagnateurs/_list_assign.html.haml
index cd7d1621a..8afe8e25f 100644
--- a/app/views/admin/accompagnateurs/_list_assign.html.haml
+++ b/app/views/admin/accompagnateurs/_list_assign.html.haml
@@ -9,7 +9,7 @@
     - @accompagnateurs_assign.each do |accompagnateur|
       %tr
         %td.col-md-1.col-lg-1.col-sm-1.col-xs-1.col-sm-1.col-xs-1.center
-          %a.btn.btn-primary{ href: "#{admin_procedure_accompagnateurs_path(procedure_id: @procedure.id, accompagnateur_id: accompagnateur.id, to: AccompagnateurService::NOT_ASSIGN)}", 'data-method' => 'put' }
+          = link_to "#{admin_procedure_accompagnateurs_path(procedure_id: @procedure.id, accompagnateur_id: accompagnateur.id, to: Admin::AccompagnateursController::NOT_ASSIGN)}", class: "btn btn-primary",  'data-method' => 'put' do
             .fa.fa-arrow-left
         %td{ style: 'padding-top: 11px; font-size: 15px; text-align: right;' }= accompagnateur.email
 
diff --git a/app/views/admin/accompagnateurs/_list_not_assign.html.haml b/app/views/admin/accompagnateurs/_list_not_assign.html.haml
index 51e8c5326..e9e156a07 100644
--- a/app/views/admin/accompagnateurs/_list_not_assign.html.haml
+++ b/app/views/admin/accompagnateurs/_list_not_assign.html.haml
@@ -16,7 +16,7 @@
       %tr
         %td.col-xs-11{ style: 'padding-top: 11px; font-size: 15px;' }= accompagnateur.email
         %td.center
-          %a.btn.btn-success.gestionnaire-affectation{ href: "#{admin_procedure_accompagnateurs_path(procedure_id: @procedure.id, accompagnateur_id: accompagnateur.id, to: AccompagnateurService::ASSIGN)}", 'data-method' => 'put' }
+          = link_to "#{admin_procedure_accompagnateurs_path(procedure_id: @procedure.id, accompagnateur_id: accompagnateur.id, to: Admin::AccompagnateursController::ASSIGN)}", class: "btn btn-success gestionnaire-affectation", 'data-method' => 'put' do
             .fa.fa-arrow-right
 
 
diff --git a/app/views/layouts/_new_header.haml b/app/views/layouts/_new_header.haml
index 3f73c7cba..f4e088c14 100644
--- a/app/views/layouts/_new_header.haml
+++ b/app/views/layouts/_new_header.haml
@@ -10,7 +10,7 @@
       - if nav_bar_profile == :gestionnaire && gestionnaire_signed_in?
         - current_url = request.path_info
         %ul.header-tabs
-          - if current_gestionnaire.procedures.count > 0
+          - if current_gestionnaire.visible_procedures.count > 0
             %li
               = link_to "Procédures", gestionnaire_procedures_path, class: (controller_name != 'avis') ? "tab-link active" : 'tab-link'
           - if current_gestionnaire.avis.count > 0
diff --git a/db/migrate/20180219170553_add_unique_index_on_assign_tos_gestionnaire_id_procedure_id.rb b/db/migrate/20180219170553_add_unique_index_on_assign_tos_gestionnaire_id_procedure_id.rb
new file mode 100644
index 000000000..77efa47ae
--- /dev/null
+++ b/db/migrate/20180219170553_add_unique_index_on_assign_tos_gestionnaire_id_procedure_id.rb
@@ -0,0 +1,5 @@
+class AddUniqueIndexOnAssignTosGestionnaireIdProcedureId < ActiveRecord::Migration[5.2]
+  def change
+    add_index :assign_tos, [:gestionnaire_id, :procedure_id], unique: true
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index d5260c7ee..41dfe638a 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2018_02_09_133452) do
+ActiveRecord::Schema.define(version: 2018_02_19_170553) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -84,6 +84,7 @@ ActiveRecord::Schema.define(version: 2018_02_09_133452) do
   create_table "assign_tos", id: :serial, force: :cascade do |t|
     t.integer "gestionnaire_id"
     t.integer "procedure_id"
+    t.index ["gestionnaire_id", "procedure_id"], name: "index_assign_tos_on_gestionnaire_id_and_procedure_id", unique: true
     t.index ["gestionnaire_id"], name: "index_assign_tos_on_gestionnaire_id"
     t.index ["procedure_id"], name: "index_assign_tos_on_procedure_id"
   end
diff --git a/spec/models/gestionnaire_spec.rb b/spec/models/gestionnaire_spec.rb
index 4c13fcb54..0a92a7bad 100644
--- a/spec/models/gestionnaire_spec.rb
+++ b/spec/models/gestionnaire_spec.rb
@@ -64,6 +64,54 @@ describe Gestionnaire, type: :model do
     end
   end
 
+  describe "#assign_to_procedure" do
+    subject { gestionnaire.assign_to_procedure(procedure_to_assign) }
+
+    context "with a procedure not already assigned" do
+      let(:procedure_to_assign) { procedure_3 }
+
+      it { is_expected.to be_truthy }
+      it { expect{ subject }.to change(gestionnaire.procedures, :count) }
+    end
+
+    context "with an already assigned procedure" do
+      let(:procedure_to_assign) { procedure }
+
+      it { is_expected.to be_falsey }
+      it { expect{ subject }.not_to change(gestionnaire.procedures, :count) }
+    end
+  end
+
+  describe "#remove_from_procedure" do
+    subject { gestionnaire.remove_from_procedure(procedure_to_remove) }
+
+    context "with an assigned procedure" do
+      let(:procedure_to_remove) { procedure }
+      let!(:procedure_presentation) { procedure_assign.procedure_presentation }
+
+      it { is_expected.to be_truthy }
+
+      describe "consequences" do
+        before do
+          procedure_assign.build_procedure_presentation
+          procedure_assign.save
+          subject
+        end
+
+        it "removes the assign_to and procedure_presentation" do
+          expect(AssignTo.where(id: procedure_assign).count).to eq(0)
+          expect(ProcedurePresentation.where(assign_to_id: procedure_assign.id).count).to eq(0)
+        end
+      end
+    end
+
+    context "with an already unassigned procedure" do
+      let(:procedure_to_remove) { procedure_3 }
+
+      it { is_expected.to be_falsey }
+    end
+  end
+
   context 'unified login' do
     it 'syncs credentials to associated user' do
       gestionnaire = create(:gestionnaire)
@@ -188,7 +236,6 @@ describe Gestionnaire, type: :model do
   end
 
   describe "procedure_presentation_for_procedure_id" do
-    let!(:procedure_assign_2) { create :assign_to, gestionnaire: gestionnaire, procedure: procedure_2 }
     let!(:pp) { ProcedurePresentation.create(assign_to: procedure_assign) }
 
     it { expect(gestionnaire.procedure_presentation_for_procedure_id(procedure.id)).to eq(pp) }
diff --git a/spec/services/accompagnateur_service_spec.rb b/spec/services/accompagnateur_service_spec.rb
deleted file mode 100644
index a5b71d612..000000000
--- a/spec/services/accompagnateur_service_spec.rb
+++ /dev/null
@@ -1,33 +0,0 @@
-require 'spec_helper'
-
-describe AccompagnateurService do
-  let(:procedure) { create :procedure, :published }
-  let(:accompagnateur) { create :gestionnaire }
-
-  let(:accompagnateur_service) { AccompagnateurService.new accompagnateur, procedure, to }
-
-  describe '#change_assignement!' do
-    subject { accompagnateur_service.change_assignement! }
-
-    context 'when accompagnateur is not assign at the procedure' do
-      let(:to) { AccompagnateurService::ASSIGN }
-
-      before do
-        subject
-      end
-
-      it { expect(accompagnateur.procedures).to include procedure }
-    end
-
-    context 'when accompagnateur is assign at the procedure' do
-      let(:to) { AccompagnateurService::NOT_ASSIGN }
-
-      before do
-        create :assign_to, gestionnaire: accompagnateur, procedure: procedure
-        subject
-      end
-
-      it { expect(accompagnateur.procedures).not_to include procedure }
-    end
-  end
-end