diff --git a/api-server/src/server/boot/certificate.js b/api-server/src/server/boot/certificate.js
index 8dcc4f6a4ce..11a5fab310f 100644
--- a/api-server/src/server/boot/certificate.js
+++ b/api-server/src/server/boot/certificate.js
@@ -14,7 +14,9 @@ import {
   certIds,
   oldDataVizId,
   currentCertifications,
-  upcomingCertifications
+  upcomingCertifications,
+  legacyCertifications,
+  legacyFullStackCertification
 } from '../../../../shared/config/certification-settings';
 import { reportError } from '../middlewares/sentry-error-handler.js';
 
@@ -77,10 +79,15 @@ export function getFallbackFullStackDate(completedChallenges, completedDate) {
   return latestCertDate ? latestCertDate : completedDate;
 }
 
-function ifNoCertification404(req, res, next) {
+export function ifNoCertification404(req, res, next) {
   const { certSlug } = req.body;
   if (!certSlug) return res.status(404).end();
-  if (currentCertifications.includes(certSlug)) return next();
+  if (
+    currentCertifications.includes(certSlug) ||
+    legacyCertifications.includes(certSlug) ||
+    legacyFullStackCertification.includes(certSlug)
+  )
+    return next();
   if (
     process.env.SHOW_UPCOMING_CHANGES === 'true' &&
     upcomingCertifications.includes(certSlug)
diff --git a/api-server/src/server/boot_tests/certificate.test.js b/api-server/src/server/boot_tests/certificate.test.js
index 4c511b6c929..556696be76c 100644
--- a/api-server/src/server/boot_tests/certificate.test.js
+++ b/api-server/src/server/boot_tests/certificate.test.js
@@ -1,10 +1,94 @@
-import { getFallbackFullStackDate } from '../boot/certificate';
+import {
+  getFallbackFullStackDate,
+  ifNoCertification404
+} from '../boot/certificate';
 import { fullStackChallenges } from './fixtures';
 
+export const mockReq = opts => {
+  const req = {};
+  return { ...req, ...opts };
+};
+
+export const mockRes = opts => {
+  const res = {};
+  res.status = jest.fn().mockReturnValue(res);
+  res.end = jest.fn().mockReturnValue(res);
+  res.json = jest.fn().mockReturnValue(res);
+  res.redirect = jest.fn().mockReturnValue(res);
+  res.set = jest.fn().mockReturnValue(res);
+  res.clearCookie = jest.fn().mockReturnValue(res);
+  res.cookie = jest.fn().mockReturnValue(res);
+  return { ...res, ...opts };
+};
+
 describe('boot/certificate', () => {
   describe('getFallbackFullStackDate', () => {
     it('should return the date of the latest completed challenge', () => {
       expect(getFallbackFullStackDate(fullStackChallenges)).toBe(1685210952511);
     });
   });
+
+  describe('ifNoCertification404', () => {
+    it('declares a 404 when there is no certSlug in the body', () => {
+      const req = mockReq({
+        body: {}
+      });
+      const res = mockRes();
+      const next = jest.fn();
+
+      ifNoCertification404(req, res, next);
+
+      expect(res.status).toHaveBeenCalledWith(404);
+      expect(next).not.toHaveBeenCalled();
+    });
+
+    it('declares a 404 for an invalid certSlug in the body', () => {
+      const req = mockReq({
+        body: { certSlug: 'not-a-real-certSlug' }
+      });
+      const res = mockRes();
+      const next = jest.fn();
+
+      ifNoCertification404(req, res, next);
+
+      expect(res.status).toHaveBeenCalledWith(404);
+      expect(next).not.toHaveBeenCalled();
+    });
+
+    it('calls next for a valid certSlug of a current certification', () => {
+      const req = mockReq({
+        body: { certSlug: 'responsive-web-design' }
+      });
+      const res = mockRes();
+      const next = jest.fn();
+
+      ifNoCertification404(req, res, next);
+
+      expect(next).toHaveBeenCalled();
+    });
+
+    it('calls next for a valid certSlug of a legacy certification', () => {
+      const req = mockReq({
+        body: { certSlug: 'legacy-front-end' }
+      });
+      const res = mockRes();
+      const next = jest.fn();
+
+      ifNoCertification404(req, res, next);
+
+      expect(next).toHaveBeenCalled();
+    });
+
+    it('calls next for a valid certSlug of the legacy full stack certification', () => {
+      const req = mockReq({
+        body: { certSlug: 'full-stack' }
+      });
+      const res = mockRes();
+      const next = jest.fn();
+
+      ifNoCertification404(req, res, next);
+
+      expect(next).toHaveBeenCalled();
+    });
+  });
 });
diff --git a/shared/config/certification-settings.ts b/shared/config/certification-settings.ts
index 0d5ecbf3925..13475ca94f3 100644
--- a/shared/config/certification-settings.ts
+++ b/shared/config/certification-settings.ts
@@ -62,6 +62,12 @@ export const legacyCertifications = [
   Certification.LegacyInfoSecQa
 ] as const;
 
+// The Legacy Full Stack certification can only be claimed when specific
+// "current" and "legacy" certifications have been claimed.
+export const legacyFullStackCertification = [
+  Certification.LegacyFullStack
+] as const;
+
 // "Upcoming" certifications are standard certifications that are not live unless
 // showUpcomingChanges is true.
 export const upcomingCertifications = [Certification.UpcomingPython] as const;