diff --git a/app/models/legislation/process.rb b/app/models/legislation/process.rb
index abf8875a7..12b195cce 100644
--- a/app/models/legislation/process.rb
+++ b/app/models/legislation/process.rb
@@ -46,13 +46,14 @@ class Legislation::Process < ApplicationRecord
   validates_translation :title, presence: true
   validates :start_date, presence: true
   validates :end_date, presence: true
-  validates :debate_start_date, presence: true, if: :debate_end_date?
-  validates :debate_end_date, presence: true, if: :debate_start_date?
-  validates :draft_start_date, presence: true, if: :draft_end_date?
-  validates :draft_end_date, presence: true, if: :draft_start_date?
-  validates :allegations_start_date, presence: true, if: :allegations_end_date?
-  validates :allegations_end_date, presence: true, if: :allegations_start_date?
-  validates :proposals_phase_end_date, presence: true, if: :proposals_phase_start_date?
+
+  %i[draft debate proposals_phase allegations].each do |phase_name|
+    enabled_attribute = :"#{phase_name.to_s.gsub("_phase", "")}_phase_enabled?"
+
+    validates :"#{phase_name}_start_date", presence: true, if: enabled_attribute
+    validates :"#{phase_name}_end_date", presence: true, if: enabled_attribute
+  end
+
   validate :valid_date_ranges
   validates :background_color, format: { allow_blank: true, with: CSS_HEX_COLOR }
   validates :font_color, format: { allow_blank: true, with: CSS_HEX_COLOR }
diff --git a/spec/models/legislation/process_spec.rb b/spec/models/legislation/process_spec.rb
index 5302497a0..0d0519407 100644
--- a/spec/models/legislation/process_spec.rb
+++ b/spec/models/legislation/process_spec.rb
@@ -18,30 +18,134 @@ describe Legislation::Process do
   end
 
   describe "dates validations" do
-    it "is invalid if debate_start_date is present but debate_end_date is not" do
-      process = build(:legislation_process, debate_start_date: Date.current, debate_end_date: "")
+    it "is invalid if draft is enabled but draft_start_date is not present" do
+      process = build(:legislation_process, draft_phase_enabled: true, draft_start_date: nil)
+
       expect(process).to be_invalid
-      expect(process.errors.messages[:debate_end_date]).to include("can't be blank")
+      expect(process.errors.messages[:draft_start_date]).to include("can't be blank")
     end
 
-    it "is invalid if debate_end_date is present but debate_start_date is not" do
-      process = build(:legislation_process, debate_start_date: nil, debate_end_date: Date.current)
+    it "is invalid if draft is enabled but draft_end_date is not present" do
+      process = build(:legislation_process, draft_phase_enabled: true, draft_end_date: "")
+
+      expect(process).to be_invalid
+      expect(process.errors.messages[:draft_end_date]).to include("can't be blank")
+    end
+
+    it "is invalid if debate phase is enabled but debate_start_date is not present" do
+      process = build(:legislation_process, debate_phase_enabled: true, debate_start_date: nil)
+
       expect(process).to be_invalid
       expect(process.errors.messages[:debate_start_date]).to include("can't be blank")
     end
 
-    it "is invalid if allegations_start_date is present but debate_end_date is not" do
-      process = build(:legislation_process, allegations_start_date: Date.current,
-                                            allegations_end_date: "")
+    it "is invalid if debate phase is enabled but debate_end_date is not present" do
+      process = build(:legislation_process, debate_phase_enabled: true, debate_end_date: "")
+
+      expect(process).to be_invalid
+      expect(process.errors.messages[:debate_end_date]).to include("can't be blank")
+    end
+
+    it "is invalid if proposals phase is enabled but proposals_phase_start_date is not present" do
+      process = build(:legislation_process, proposals_phase_enabled: true, proposals_phase_start_date: nil)
+
+      expect(process).to be_invalid
+      expect(process.errors.messages[:proposals_phase_start_date]).to include("can't be blank")
+    end
+
+    it "is invalid if proposals phase is enabled but proposals_phase_end_date is not present" do
+      process = build(:legislation_process, proposals_phase_enabled: true, proposals_phase_end_date: "")
+
+      expect(process).to be_invalid
+      expect(process.errors.messages[:proposals_phase_end_date]).to include("can't be blank")
+    end
+
+    it "is invalid if allegations phase is enabled but allegations_start_date is not present" do
+      process = build(:legislation_process, allegations_phase_enabled: true,
+                                            allegations_start_date: nil,)
+
+      expect(process).to be_invalid
+      expect(process.errors.messages[:allegations_start_date]).to include("can't be blank")
+    end
+
+    it "is invalid if allegations phase is enabled but allegations_end_date is not present" do
+      process = build(:legislation_process, allegations_phase_enabled: true, allegations_end_date: "")
+
       expect(process).to be_invalid
       expect(process.errors.messages[:allegations_end_date]).to include("can't be blank")
     end
 
-    it "is invalid if debate_end_date is present but allegations_start_date is not" do
-      process = build(:legislation_process, allegations_start_date: nil,
-                                            allegations_end_date: Date.current)
-      expect(process).to be_invalid
-      expect(process.errors.messages[:allegations_start_date]).to include("can't be blank")
+    it "is valid if start dates are missing and the phase is disabled" do
+      draft_disabled = build(:legislation_process,
+                             draft_phase_enabled: false,
+                             draft_start_date: nil)
+
+      debate_disabled = build(:legislation_process,
+                              debate_phase_enabled: false,
+                              debate_start_date: nil)
+
+      proposals_disabled = build(:legislation_process,
+                                 proposals_phase_enabled: false,
+                                 proposals_phase_start_date: nil)
+
+      allegations_disabled = build(:legislation_process,
+                                   allegations_phase_enabled: false,
+                                   allegations_start_date: nil)
+
+      expect(draft_disabled).to be_valid
+      expect(debate_disabled).to be_valid
+      expect(proposals_disabled).to be_valid
+      expect(allegations_disabled).to be_valid
+    end
+
+    it "is valid if end dates are missing and the phase is disabled" do
+      draft_disabled = build(:legislation_process,
+                             draft_phase_enabled: false,
+                             draft_end_date: nil)
+
+      debate_disabled = build(:legislation_process,
+                              debate_phase_enabled: false,
+                              debate_end_date: nil)
+
+      proposals_disabled = build(:legislation_process,
+                                 proposals_phase_enabled: false,
+                                 proposals_phase_end_date: nil)
+
+      allegations_disabled = build(:legislation_process,
+                                   allegations_phase_enabled: false,
+                                   allegations_end_date: nil)
+
+      expect(draft_disabled).to be_valid
+      expect(debate_disabled).to be_valid
+      expect(proposals_disabled).to be_valid
+      expect(allegations_disabled).to be_valid
+    end
+
+    it "is valid if start and end dates are missing and the phase is disabled" do
+      draft_disabled = build(:legislation_process,
+                             draft_phase_enabled: false,
+                             draft_start_date: nil,
+                             draft_end_date: nil)
+
+      debate_disabled = build(:legislation_process,
+                              debate_phase_enabled: false,
+                              debate_start_date: nil,
+                              debate_end_date: nil)
+
+      proposals_disabled = build(:legislation_process,
+                                 proposals_phase_enabled: false,
+                                 proposals_phase_start_date: nil,
+                                 proposals_phase_end_date: nil)
+
+      allegations_disabled = build(:legislation_process,
+                                   allegations_phase_enabled: false,
+                                   allegations_start_date: nil,
+                                   allegations_end_date: nil)
+
+      expect(draft_disabled).to be_valid
+      expect(debate_disabled).to be_valid
+      expect(proposals_disabled).to be_valid
+      expect(allegations_disabled).to be_valid
     end
   end
 
diff --git a/spec/system/admin/legislation/processes_spec.rb b/spec/system/admin/legislation/processes_spec.rb
index 1ce14063c..432a3baad 100644
--- a/spec/system/admin/legislation/processes_spec.rb
+++ b/spec/system/admin/legislation/processes_spec.rb
@@ -289,6 +289,24 @@ describe "Admin collaborative legislation", :admin do
       expect(page).to have_field "draft_publication_date", disabled: true
     end
 
+    scenario "Enabling comments phase with blank dates" do
+      visit edit_admin_legislation_process_path(process)
+
+      within_fieldset "Comments phase" do
+        check "Enabled"
+        fill_in "Start", with: ""
+        fill_in "End", with: ""
+      end
+
+      click_button "Save changes"
+
+      expect(page).to have_content "errors prevented this process from being saved"
+
+      within_fieldset "Comments phase" do
+        expect(page).to have_content "can't be blank"
+      end
+    end
+
     scenario "Change proposal categories" do
       visit edit_admin_legislation_process_path(process)
       within(".admin-content") { click_link "Proposals" }