diff --git a/index.html b/index.html
index 5b24bea..09d905d 100644
--- a/index.html
+++ b/index.html
@@ -41,6 +41,28 @@
     // Show the instructions/form when JavaScript is enabled
     document.querySelector(".container").style.display = "block";
   });
+
+  // Custom validation for select elements
+  document.getElementById("contact-form").addEventListener("submit", function(event) {
+    if (!this.checkValidity()) {
+      // Built-in validation failed, no need to continue
+      return;
+    }
+
+    // Custom validation for select elements
+    var selectElements = this.querySelectorAll("select[required]");
+    for (var i = 0; i < selectElements.length; i++) {
+      if (selectElements[i].value === "") {
+        event.preventDefault(); // Prevent form submission
+        alert("Please select a value.");
+
+        // Scroll to the element
+        selectElements[i].scrollIntoView({ behavior: "smooth", block: "center" });
+
+        return;
+      }
+    }
+  });
 </script>
 </body>
 </html>
diff --git a/tests/test_fixtures.py b/tests/test_fixtures.py
index ababb42..f204c02 100644
--- a/tests/test_fixtures.py
+++ b/tests/test_fixtures.py
@@ -182,3 +182,38 @@ def test_multi_options_config_schema(
     assert check_config_schema(
         multiple_select_options_config
     ), "Error in multi options config fixture."
+
+
+@pytest.mark.fixture
+def test_multi_opts_config_multiple(
+    multiple_select_options_config: Dict[str, Any]
+) -> None:
+    """Confirm that the multi selection options config has multiple options."""
+    # get questions
+    question = multiple_select_options_config["questions"][0]
+
+    # check multiple options
+    assert len(question["options"]) > 1
+
+    # check custom.multiple attr set
+    assert question["custom"]["multiple"]
+
+
+@pytest.mark.fixture
+def test_multi_opts_config_defaults(
+    multiple_select_options_config: Dict[str, Any]
+) -> None:
+    """Check that at least one options is selected and disabled."""
+    # get options
+    options = multiple_select_options_config["questions"][0]["options"]
+
+    # results store
+    results = []
+
+    # loop over options
+    for opt in options:
+        # check for default
+        results.append(opt.get("selected", False) and opt.get("disabled", False))
+
+    # now check results
+    assert any(results)
diff --git a/tests/test_website.py b/tests/test_website.py
index e1460a6..6b914e8 100644
--- a/tests/test_website.py
+++ b/tests/test_website.py
@@ -491,7 +491,6 @@ def test_form_download_required_constraint(
     sb.save_screenshot_to_logs()
 
 
-@pytest.mark.debug
 @pytest.mark.feature
 def test_select_multiple_options(
     sb: BaseCase,
@@ -571,3 +570,55 @@ def test_select_multiple_options(
 
     # save screenshot for confirmation of submission
     sb.save_screenshot_to_logs()
+
+
+@pytest.mark.feature
+def test_select_default_submission_rejected(
+    sb: BaseCase,
+    live_function_web_app_url: str,
+    submit_route: str,
+    function_websrc_tmp_dir: Path,
+    function_web_app: Flask,
+    multiple_select_options_config: Dict[str, Any],
+) -> None:
+    """Confirm that default select options will not pass for submission."""
+    # add form backend
+    multiple_select_options_config["form_backend_url"] = (
+        live_function_web_app_url + submit_route
+    )
+
+    # update config file for testing multi select options
+    write_config_file(multiple_select_options_config, function_websrc_tmp_dir)
+
+    # open site
+    sb.open(live_function_web_app_url)
+
+    # get form
+    form_element = sb.get_element("form")
+
+    # get send button ...
+    send_button = form_element.find_element(By.ID, "send_button")
+
+    # store page source before
+    page_source = {"before": sb.get_page_source()}
+
+    # get screenshot
+    sb.save_screenshot_to_logs()
+
+    # ... now click it
+    send_button.click()
+
+    # switch to the alert and get its text
+    alert_text = sb.switch_to_alert().text
+
+    # now accept it
+    sb.accept_alert()
+
+    # make sure alert texts match
+    assert alert_text == "Please select a value."
+
+    # now store it after
+    page_source["after"] = sb.get_page_source()
+
+    # should NOT see contact form response
+    assert page_source["before"] == page_source["after"]