diff --git a/app/controllers/gestionnaires/dossiers_controller.rb b/app/controllers/gestionnaires/dossiers_controller.rb
index 764f24b6c..d58fed8fb 100644
--- a/app/controllers/gestionnaires/dossiers_controller.rb
+++ b/app/controllers/gestionnaires/dossiers_controller.rb
@@ -3,6 +3,7 @@ module Gestionnaires
     include ActionView::Helpers::NumberHelper
     include ActionView::Helpers::TextHelper
     include CreateAvisConcern
+    include DossierHelper
 
     after_action :mark_demande_as_read, only: :show
     after_action :mark_messagerie_as_read, only: [:messagerie, :create_commentaire]
@@ -91,15 +92,23 @@ module Gestionnaires
     end
 
     def repasser_en_construction
-      dossier.repasser_en_construction!(current_gestionnaire)
-      flash.notice = 'Dossier repassé en construction.'
+      if dossier.en_construction?
+        flash.notice = 'Le dossier est déjà en construction.'
+      else
+        dossier.repasser_en_construction!(current_gestionnaire)
+        flash.notice = 'Dossier repassé en construction.'
+      end
 
       render partial: 'state_button_refresh', locals: { dossier: dossier }
     end
 
     def repasser_en_instruction
-      flash.notice = "Le dossier #{dossier.id} a été repassé en instruction."
-      dossier.repasser_en_instruction!(current_gestionnaire)
+      if dossier.en_instruction?
+        flash.notice = 'Le dossier est déjà en instruction.'
+      else
+        flash.notice = "Le dossier #{dossier.id} a été repassé en instruction."
+        dossier.repasser_en_instruction!(current_gestionnaire)
+      end
 
       render partial: 'state_button_refresh', locals: { dossier: dossier }
     end
@@ -108,16 +117,20 @@ module Gestionnaires
       motivation = params[:dossier] && params[:dossier][:motivation]
       justificatif = params[:dossier] && params[:dossier][:justificatif_motivation]
 
-      case params[:process_action]
-      when "refuser"
-        dossier.refuser!(current_gestionnaire, motivation, justificatif)
-        flash.notice = "Dossier considéré comme refusé."
-      when "classer_sans_suite"
-        dossier.classer_sans_suite!(current_gestionnaire, motivation, justificatif)
-        flash.notice = "Dossier considéré comme sans suite."
-      when "accepter"
-        dossier.accepter!(current_gestionnaire, motivation, justificatif)
-        flash.notice = "Dossier traité avec succès."
+      if dossier.termine?
+        flash.notice = "Le dossier est déjà #{dossier_display_state(dossier, lower: true)}"
+      else
+        case params[:process_action]
+        when "refuser"
+          dossier.refuser!(current_gestionnaire, motivation, justificatif)
+          flash.notice = "Dossier considéré comme refusé."
+        when "classer_sans_suite"
+          dossier.classer_sans_suite!(current_gestionnaire, motivation, justificatif)
+          flash.notice = "Dossier considéré comme sans suite."
+        when "accepter"
+          dossier.accepter!(current_gestionnaire, motivation, justificatif)
+          flash.notice = "Dossier traité avec succès."
+        end
       end
 
       render partial: 'state_button_refresh', locals: { dossier: dossier }
diff --git a/spec/controllers/gestionnaires/dossiers_controller_spec.rb b/spec/controllers/gestionnaires/dossiers_controller_spec.rb
index 532913960..cbf5b775a 100644
--- a/spec/controllers/gestionnaires/dossiers_controller_spec.rb
+++ b/spec/controllers/gestionnaires/dossiers_controller_spec.rb
@@ -128,21 +128,51 @@ describe Gestionnaires::DossiersController, type: :controller do
   end
 
   describe '#repasser_en_construction' do
+    let(:dossier) { create(:dossier, :en_instruction, procedure: procedure) }
+
     before do
-      dossier.en_instruction!
       sign_in gestionnaire
+      post :repasser_en_construction,
+        params: { procedure_id: procedure.id, dossier_id: dossier.id },
+        format: 'js'
     end
 
-    subject { post :repasser_en_construction, params: { procedure_id: procedure.id, dossier_id: dossier.id }, format: 'js' }
+    it { expect(dossier.reload.state).to eq(Dossier.states.fetch(:en_construction)) }
+    it { expect(response).to have_http_status(:ok) }
+    it { expect(response.body).to include('.state-button') }
 
-    it 'change state to en_construction' do
-      subject
+    context 'when the dossier has already been put en_construction' do
+      let(:dossier) { create(:dossier, :en_construction, procedure: procedure) }
 
-      dossier.reload
-      expect(dossier.state).to eq(Dossier.states.fetch(:en_construction))
+      it 'warns about the error, but doesn’t raise' do
+        expect(dossier.reload.state).to eq(Dossier.states.fetch(:en_construction))
+        expect(response).to have_http_status(:ok)
+      end
+    end
+  end
+
+  describe '#repasser_en_instruction' do
+    let(:dossier) { create(:dossier, :refuse, procedure: procedure) }
+
+    before do
+      sign_in gestionnaire
+      post :repasser_en_instruction,
+        params: { procedure_id: procedure.id, dossier_id: dossier.id },
+        format: 'js'
     end
 
-    it { expect(subject.body).to include('.state-button') }
+    it { expect(dossier.reload.state).to eq(Dossier.states.fetch(:en_instruction)) }
+    it { expect(response).to have_http_status(:ok) }
+    it { expect(response.body).to include('.state-button') }
+
+    context 'when the dossier has already been put en_instruction' do
+      let(:dossier) { create(:dossier, :en_instruction, procedure: procedure) }
+
+      it 'warns about the error, but doesn’t raise' do
+        expect(dossier.reload.state).to eq(Dossier.states.fetch(:en_instruction))
+        expect(response).to have_http_status(:ok)
+      end
+    end
   end
 
   describe '#terminer' do
@@ -319,6 +349,21 @@ describe Gestionnaires::DossiersController, type: :controller do
         it { expect(subject.body).to include('.state-button') }
       end
     end
+
+    context 'when a dossier is already closed' do
+      let(:dossier) { create(:dossier, :accepte, procedure: procedure) }
+
+      before { allow(dossier).to receive(:accepter!) }
+
+      subject { post :terminer, params: { process_action: "accepter", procedure_id: procedure.id, dossier_id: dossier.id, dossier: { justificatif_motivation: fake_justificatif } }, format: 'js' }
+
+      it 'does not close it again' do
+        subject
+
+        expect(dossier).not_to have_received(:accepter!)
+        expect(response).to have_http_status(:ok)
+      end
+    end
   end
 
   describe "#create_commentaire" do