diff --git a/devtools/shim/DevToolsShim.jsm b/devtools/shim/DevToolsShim.jsm
index cefaa837c28a..df77e7a3de48 100644
--- a/devtools/shim/DevToolsShim.jsm
+++ b/devtools/shim/DevToolsShim.jsm
@@ -14,6 +14,7 @@ XPCOMUtils.defineLazyGetter(this, "DevtoolsStartup", () => {
 });
 
 const DEVTOOLS_ENABLED_PREF = "devtools.enabled";
+const DEVTOOLS_POLICY_DISABLED_PREF = "devtools.policy.disabled";
 
 this.EXPORTED_SYMBOLS = [
   "DevToolsShim",
@@ -61,7 +62,16 @@ this.DevToolsShim = {
    * should no-op in this case.
    */
   isEnabled: function () {
-    return Services.prefs.getBoolPref(DEVTOOLS_ENABLED_PREF);
+    let enabled = Services.prefs.getBoolPref(DEVTOOLS_ENABLED_PREF);
+    return enabled && !this.isDisabledByPolicy();
+  },
+
+  /**
+   * Returns true if the devtools are completely disabled and can not be enabled. All
+   * entry points should return without throwing, initDevTools should never be called.
+   */
+  isDisabledByPolicy: function () {
+    return Services.prefs.getBoolPref(DEVTOOLS_POLICY_DISABLED_PREF, false);
   },
 
   /**
@@ -179,7 +189,9 @@ this.DevToolsShim = {
    */
   inspectNode: function (tab, selectors) {
     if (!this.isEnabled()) {
-      DevtoolsStartup.openInstallPage("ContextMenu");
+      if (!this.isDisabledByPolicy()) {
+        DevtoolsStartup.openInstallPage("ContextMenu");
+      }
       return Promise.resolve();
     }
 
diff --git a/devtools/shim/tests/unit/test_devtools_shim.js b/devtools/shim/tests/unit/test_devtools_shim.js
index df1e49e02478..263c12e76642 100644
--- a/devtools/shim/tests/unit/test_devtools_shim.js
+++ b/devtools/shim/tests/unit/test_devtools_shim.js
@@ -141,15 +141,28 @@ function test_restore_session_apis() {
     browserConsole: true,
   };
 
-  Services.prefs.setBoolPref("devtools.enabled", false);
-  ok(!DevToolsShim.isInitialized(), "DevTools are not initialized");
-  ok(!DevToolsShim.isEnabled(), "DevTools are not enabled");
+  function checkRestoreSessionNotApplied(policyDisabled, enabled) {
+    Services.prefs.setBoolPref("devtools.enabled", enabled);
+    Services.prefs.setBoolPref("devtools.policy.disabled", policyDisabled);
+    ok(!DevToolsShim.isInitialized(), "DevTools are not initialized");
+    ok(!DevToolsShim.isEnabled(), "DevTools are not enabled");
 
-  // Check that save & restore DevToolsSession don't initialize the tools and don't crash.
-  DevToolsShim.saveDevToolsSession({});
-  DevToolsShim.restoreDevToolsSession(sessionWithDevTools);
+    // Check that save & restore DevToolsSession don't initialize the tools and don't
+    // crash.
+    DevToolsShim.saveDevToolsSession({});
+    DevToolsShim.restoreDevToolsSession(sessionWithDevTools);
+    ok(!DevToolsShim.isInitialized(), "DevTools are still not initialized");
+  }
+
+  // Tools are disabled by policy and not enabled
+  checkRestoreSessionNotApplied(true, false);
+  // Tools are not disabled by policy, but not enabled
+  checkRestoreSessionNotApplied(false, false);
+  // Tools are disabled by policy and "considered" as enabled (see Bug 1440675)
+  checkRestoreSessionNotApplied(true, true);
 
   Services.prefs.setBoolPref("devtools.enabled", true);
+  Services.prefs.setBoolPref("devtools.policy.disabled", false);
   ok(DevToolsShim.isEnabled(), "DevTools are enabled");
   ok(!DevToolsShim.isInitialized(), "DevTools are not initialized");