diff --git a/__tests__/verifier.tests.ts b/__tests__/verifier.tests.ts
index d3785e2..bf0807d 100644
--- a/__tests__/verifier.tests.ts
+++ b/__tests__/verifier.tests.ts
@@ -31,8 +31,11 @@ describe('verifier', () => {
           ephemeralReaderKey,
           encodedSessionTranscript,
           onCheck: (verification) => {
-            if (verification.check.includes('Issuer certificate must be valid') &&
-              verification.status === 'FAILED') {
+            if (
+              verification.id === 'ISSUER_CERTIFICATE_VALIDITY' &&
+              verification.check.includes('Issuer certificate must be valid') &&
+              verification.status === 'FAILED'
+            ) {
               called = true;
             }
           },
diff --git a/src/index.ts b/src/index.ts
index 666696b..9299221 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -7,4 +7,5 @@ export { Document } from './mdoc/model/Document';
 export { IssuerSignedDocument } from './mdoc/model/IssuerSignedDocument';
 export { DeviceSignedDocument } from './mdoc/model/DeviceSignedDocument';
 export { DeviceResponse } from './mdoc/model/DeviceResponse';
-export { MDLError, MDLParseError } from './mdoc/errors'
+export { MDLError, MDLParseError } from './mdoc/errors';
+export { VerificationAssessmentId } from './mdoc/checkCallback';
diff --git a/src/mdoc/Verifier.ts b/src/mdoc/Verifier.ts
index 462b39f..0dddb7a 100644
--- a/src/mdoc/Verifier.ts
+++ b/src/mdoc/Verifier.ts
@@ -14,7 +14,7 @@ import {
 import {
   DiagnosticInformation,
 } from './model/types';
-import { UserDefinedVerificationCallback, VerificationAssessment, buildCallback, onCatCheck } from './checkCallback';
+import { UserDefinedVerificationCallback, VerificationAssessment, VerificationAssessmentId, buildCallback, onCatCheck } from './checkCallback';
 
 import { parse } from './parser';
 import IssuerAuth from './model/IssuerAuth';
@@ -54,11 +54,13 @@ export class Verifier {
         onCheck({
           status: 'PASSED',
           check: 'Issuer certificate must be valid',
+          id: VerificationAssessmentId.ISSUER_AUTH.IssuerCertificateValidity,
         });
       } catch (err) {
         onCheck({
           status: 'FAILED',
           check: 'Issuer certificate must be valid',
+          id: VerificationAssessmentId.ISSUER_AUTH.IssuerCertificateValidity,
           reason: err.message,
         });
       }
@@ -68,6 +70,7 @@ export class Verifier {
     onCheck({
       status: verificationResult ? 'PASSED' : 'FAILED',
       check: 'Issuer signature must be valid',
+      id: VerificationAssessmentId.ISSUER_AUTH.IssuerSignatureValidity,
     });
 
     // Validity
@@ -77,18 +80,21 @@ export class Verifier {
     onCheck({
       status: certificate && validityInfo && (validityInfo.signed < certificate.notBefore || validityInfo.signed > certificate.notAfter) ? 'FAILED' : 'PASSED',
       check: 'The MSO signed date must be within the validity period of the certificate',
+      id: VerificationAssessmentId.ISSUER_AUTH.MsoSignedDateWithinCertificateValidity,
       reason: `The MSO signed date (${validityInfo.signed.toUTCString()}) must be within the validity period of the certificate (${certificate.notBefore.toUTCString()} to ${certificate.notAfter.toUTCString()})`,
     });
 
     onCheck({
       status: validityInfo && (now < validityInfo.validFrom || now > validityInfo.validUntil) ? 'FAILED' : 'PASSED',
       check: 'The MSO must be valid at the time of verification',
+      id: VerificationAssessmentId.ISSUER_AUTH.MsoValidityAtVerificationTime,
       reason: `The MSO must be valid at the time of verification (${now.toUTCString()})`,
     });
 
     onCheck({
       status: countryName ? 'PASSED' : 'FAILED',
       check: 'Country name (C) must be present in the issuer certificate\'s subject distinguished name',
+      id: VerificationAssessmentId.ISSUER_AUTH.IssuerSubjectCountryNamePresence,
     });
   }
 
@@ -106,6 +112,7 @@ export class Verifier {
       onCheck({
         status: 'FAILED',
         check: 'The document is not signed by the device.',
+        id: VerificationAssessmentId.DEVICE_AUTH.DocumentDeviceSignaturePresence,
       });
       return;
     }
@@ -119,6 +126,7 @@ export class Verifier {
       onCheck({
         status: 'FAILED',
         check: 'Device Auth must contain a deviceSignature or deviceMac element',
+        id: VerificationAssessmentId.DEVICE_AUTH.DeviceAuthSignatureOrMacPresence,
       });
       return;
     }
@@ -127,6 +135,7 @@ export class Verifier {
       onCheck({
         status: 'FAILED',
         check: 'Session Transcript Bytes missing from options, aborting device signature check',
+        id: VerificationAssessmentId.DEVICE_AUTH.SessionTranscriptProvided,
       });
       return;
     }
@@ -141,6 +150,7 @@ export class Verifier {
       onCheck({
         status: 'FAILED',
         check: 'Issuer signature must contain the device key.',
+        id: VerificationAssessmentId.DEVICE_AUTH.DeviceKeyAvailableInIssuerAuth,
         reason: 'Unable to verify deviceAuth signature: missing device key in issuerAuth',
       });
       return;
@@ -163,11 +173,13 @@ export class Verifier {
         onCheck({
           status: verificationResult ? 'PASSED' : 'FAILED',
           check: 'Device signature must be valid',
+          id: VerificationAssessmentId.DEVICE_AUTH.DeviceSignatureValidity,
         });
       } catch (err) {
         onCheck({
           status: 'FAILED',
           check: 'Device signature must be valid',
+          id: VerificationAssessmentId.DEVICE_AUTH.DeviceSignatureValidity,
           reason: `Unable to verify deviceAuth signature (ECDSA/EdDSA): ${err.message}`,
         });
       }
@@ -178,18 +190,21 @@ export class Verifier {
     onCheck({
       status: deviceAuth.deviceMac ? 'PASSED' : 'FAILED',
       check: 'Device MAC must be present when using MAC authentication',
+      id: VerificationAssessmentId.DEVICE_AUTH.DeviceMacPresence,
     });
     if (!deviceAuth.deviceMac) { return; }
 
     onCheck({
       status: deviceAuth.deviceMac.hasSupportedAlg() ? 'PASSED' : 'FAILED',
       check: 'Device MAC must use alg 5 (HMAC 256/256)',
+      id: VerificationAssessmentId.DEVICE_AUTH.DeviceMacAlgorithmCorrectness,
     });
     if (!deviceAuth.deviceMac.hasSupportedAlg()) { return; }
 
     onCheck({
       status: options.ephemeralPrivateKey ? 'PASSED' : 'FAILED',
       check: 'Ephemeral private key must be present when using MAC authentication',
+      id: VerificationAssessmentId.DEVICE_AUTH.EphemeralKeyPresence,
     });
     if (!options.ephemeralPrivateKey) { return; }
 
@@ -209,11 +224,13 @@ export class Verifier {
       onCheck({
         status: isValid ? 'PASSED' : 'FAILED',
         check: 'Device MAC must be valid',
+        id: VerificationAssessmentId.DEVICE_AUTH.DeviceMacValidity,
       });
     } catch (err) {
       onCheck({
         status: 'FAILED',
         check: 'Device MAC must be valid',
+        id: VerificationAssessmentId.DEVICE_AUTH.DeviceMacValidity,
         reason: `Unable to verify deviceAuth MAC: ${err.message}`,
       });
     }
@@ -231,6 +248,7 @@ export class Verifier {
     onCheck({
       status: digestAlgorithm && DIGEST_ALGS[digestAlgorithm] ? 'PASSED' : 'FAILED',
       check: 'Issuer Auth must include a supported digestAlgorithm element',
+      id: VerificationAssessmentId.DATA_INTEGRITY.IssuerAuthDigestAlgorithmSupported,
     });
 
     const nameSpaces = mdoc.issuerSigned.nameSpaces || {};
@@ -239,6 +257,7 @@ export class Verifier {
       onCheck({
         status: valueDigests.has(ns) ? 'PASSED' : 'FAILED',
         check: `Issuer Auth must include digests for namespace: ${ns}`,
+        id: VerificationAssessmentId.DATA_INTEGRITY.IssuerAuthNamespaceDigestPresence,
       });
 
       const verifications = await Promise.all(nameSpaces[ns].map(async (ev) => {
@@ -250,6 +269,7 @@ export class Verifier {
         onCheck({
           status: 'PASSED',
           check: `The calculated digest for ${ns}/${v.ev.elementIdentifier} attribute must match the digest in the issuerAuth element`,
+          id: VerificationAssessmentId.DATA_INTEGRITY.AttributeDigestMatch,
         });
       });
 
@@ -257,6 +277,7 @@ export class Verifier {
         onCheck({
           status: 'FAILED',
           check: `The calculated digest for ${ns}/${v.ev.elementIdentifier} attribute must match the digest in the issuerAuth element`,
+          id: VerificationAssessmentId.DATA_INTEGRITY.AttributeDigestMatch,
         });
       });
 
@@ -266,6 +287,7 @@ export class Verifier {
           onCheck({
             status: 'FAILED',
             check: "The 'issuing_country' if present must match the 'countryName' in the subject field within the DS certificate",
+            id: VerificationAssessmentId.DATA_INTEGRITY.IssuingCountryMatchesCertificate,
             reason: "The 'issuing_country' and 'issuing_jurisdiction' cannot be verified because the DS certificate was not provided",
           });
         } else {
@@ -275,6 +297,7 @@ export class Verifier {
           onCheck({
             status: invalidCountry ? 'FAILED' : 'PASSED',
             check: "The 'issuing_country' if present must match the 'countryName' in the subject field within the DS certificate",
+            id: VerificationAssessmentId.DATA_INTEGRITY.IssuingCountryMatchesCertificate,
             reason: invalidCountry ?
               `The 'issuing_country' (${invalidCountry.ev.elementValue}) must match the 'countryName' (${issuerAuth.countryName}) in the subject field within the issuer certificate` :
               undefined,
@@ -286,6 +309,7 @@ export class Verifier {
           onCheck({
             status: invalidJurisdiction ? 'FAILED' : 'PASSED',
             check: "The 'issuing_jurisdiction' if present must match the 'stateOrProvinceName' in the subject field within the DS certificate",
+            id: VerificationAssessmentId.DATA_INTEGRITY.IssuingJurisdictionMatchesCertificate,
             reason: invalidJurisdiction ?
               `The 'issuing_jurisdiction' (${invalidJurisdiction.ev.elementValue}) must match the 'stateOrProvinceName' (${issuerAuth.stateOrProvince}) in the subject field within the issuer certificate` :
               undefined,
@@ -318,18 +342,21 @@ export class Verifier {
     onCheck({
       status: dr.version ? 'PASSED' : 'FAILED',
       check: 'Device Response must include "version" element.',
+      id: VerificationAssessmentId.DOCUMENT_FORMAT.DeviceResponseVersionPresence,
       category: 'DOCUMENT_FORMAT',
     });
 
     onCheck({
       status: compareVersions(dr.version, '1.0') >= 0 ? 'PASSED' : 'FAILED',
       check: 'Device Response version must be 1.0 or greater',
+      id: VerificationAssessmentId.DOCUMENT_FORMAT.DeviceResponseVersionSupported,
       category: 'DOCUMENT_FORMAT',
     });
 
     onCheck({
       status: dr.documents && dr.documents.length > 0 ? 'PASSED' : 'FAILED',
       check: 'Device Response must include at least one document.',
+      id: VerificationAssessmentId.DOCUMENT_FORMAT.DeviceResponseDocumentPresence,
       category: 'DOCUMENT_FORMAT',
     });
 
@@ -359,6 +386,7 @@ export class Verifier {
   ): Promise<DiagnosticInformation> {
     const dr: VerificationAssessment[] = [];
     const decoded = await this.verify(
+      // @ts-ignore
       encodedDeviceResponse,
       {
         ...options,
diff --git a/src/mdoc/checkCallback.ts b/src/mdoc/checkCallback.ts
index 896e30a..143b4e9 100644
--- a/src/mdoc/checkCallback.ts
+++ b/src/mdoc/checkCallback.ts
@@ -3,12 +3,52 @@ import { MDLError } from './errors';
 
 const log = debug('mdl');
 
+export const VerificationAssessmentId = {
+  ISSUER_AUTH: {
+    IssuerCertificateValidity: 'ISSUER_CERTIFICATE_VALIDITY',
+    IssuerSignatureValidity: 'ISSUER_SIGNATURE_VALIDITY',
+    MsoSignedDateWithinCertificateValidity: 'MSO_SIGNED_DATE_WITHIN_CERTIFICATE_VALIDITY',
+    MsoValidityAtVerificationTime: 'MSO_VALIDITY_AT_VERIFICATION_TIME',
+    IssuerSubjectCountryNamePresence: 'ISSUER_SUBJECT_COUNTRY_NAME_PRESENCE',
+  },
+
+  DEVICE_AUTH: {
+    DocumentDeviceSignaturePresence: 'DOCUMENT_DEVICE_SIGNATURE_PRESENCE',
+    DeviceAuthSignatureOrMacPresence: 'DEVICE_AUTH_SIGNATURE_OR_MAC_PRESENCE',
+    SessionTranscriptProvided: 'SESSION_TRANSCRIPT_PROVIDED',
+    DeviceKeyAvailableInIssuerAuth: 'DEVICE_KEY_AVAILABLE_IN_ISSUERAUTH',
+    DeviceSignatureValidity: 'DEVICE_SIGNATURE_VALIDITY',
+    DeviceMacPresence: 'DEVICE_MAC_PRESENCE',
+    DeviceMacAlgorithmCorrectness: 'DEVICE_MAC_ALGORITHM_CORRECTNESS',
+    EphemeralKeyPresence: 'EPHEMERAL_KEY_PRESENCE',
+    DeviceMacValidity: 'DEVICE_MAC_VALIDITY',
+  },
+
+  DATA_INTEGRITY: {
+    IssuerAuthDigestAlgorithmSupported: 'ISSUER_AUTH_DIGEST_ALGORITHM_SUPPORTED',
+    IssuerAuthNamespaceDigestPresence: 'ISSUER_AUTH_NAMESPACE_DIGEST_PRESENCE',
+    AttributeDigestMatch: 'ATTRIBUTE_DIGEST_MATCH',
+    IssuingCountryMatchesCertificate: 'ISSUING_COUNTRY_MATCHES_CERTIFICATE',
+    IssuingJurisdictionMatchesCertificate: 'ISSUING_JURISDICTION_MATCHES_CERTIFICATE',
+  },
+
+  DOCUMENT_FORMAT: {
+    DeviceResponseVersionPresence: 'DEVICE_RESPONSE_VERSION_PRESENCE',
+    DeviceResponseVersionSupported: 'DEVICE_RESPONSE_VERSION_SUPPORTED',
+    DeviceResponseDocumentPresence: 'DEVICE_RESPONSE_DOCUMENT_PRESENCE',
+  },
+} as const;
+
 export type VerificationAssessment = {
   status: 'PASSED' | 'FAILED' | 'WARNING',
-  category: 'DOCUMENT_FORMAT' | 'DEVICE_AUTH' | 'ISSUER_AUTH' | 'DATA_INTEGRITY',
   check: string,
   reason?: string,
-};
+} & {
+  [C in keyof typeof VerificationAssessmentId]: {
+    category: C;
+    id: typeof VerificationAssessmentId[C][keyof typeof VerificationAssessmentId[C]];
+  };
+}[keyof typeof VerificationAssessmentId];
 
 export type VerificationCallback = (item: VerificationAssessment) => void;
 export type UserDefinedVerificationCallback = (item: VerificationAssessment, original: VerificationCallback) => void;
@@ -16,7 +56,7 @@ export type UserDefinedVerificationCallback = (item: VerificationAssessment, ori
 export const defaultCallback: VerificationCallback = ((verification) => {
   log(`Verification: ${verification.check} => ${verification.status}`);
   if (verification.status !== 'FAILED') return;
-  throw new MDLError(verification.reason ?? verification.check);
+  throw new MDLError(verification.reason ?? verification.check, verification.id);
 });
 
 export const buildCallback = (callback?: UserDefinedVerificationCallback): VerificationCallback => {
@@ -26,8 +66,8 @@ export const buildCallback = (callback?: UserDefinedVerificationCallback): Verif
   };
 };
 
-export const onCatCheck = (onCheck: UserDefinedVerificationCallback, category: VerificationAssessment['category']) => {
-  return (item: Omit<VerificationAssessment, 'category'>) => {
-    onCheck({ ...item, category }, defaultCallback);
+export const onCatCheck = <C extends keyof typeof VerificationAssessmentId>(onCheck: UserDefinedVerificationCallback, category: C) => {
+  return (item: Omit<Extract<VerificationAssessment, { category: C }>, 'category'>) => {
+    onCheck({ ...item, category } as VerificationAssessment, defaultCallback);
   };
 };
diff --git a/src/mdoc/errors.ts b/src/mdoc/errors.ts
index 4d4ccfa..bbb437f 100644
--- a/src/mdoc/errors.ts
+++ b/src/mdoc/errors.ts
@@ -1,7 +1,10 @@
 export class MDLError extends Error {
-  constructor(message?: string) {
+  public code?: string;
+
+  constructor(message: string, code?: string) {
     super(message);
     this.name = new.target.name;
+    this.code = code;
     Object.setPrototypeOf(this, new.target.prototype);
   }
 }