diff --git a/Packages/ohif-measurements/client/conformance/CriteriaEvaluator.js b/Packages/ohif-measurements/client/conformance/CriteriaEvaluator.js
index 24e6f5085..e2a21eba1 100644
--- a/Packages/ohif-measurements/client/conformance/CriteriaEvaluator.js
+++ b/Packages/ohif-measurements/client/conformance/CriteriaEvaluator.js
@@ -6,30 +6,12 @@ import Ajv from 'ajv';
 export class CriteriaEvaluator {
 
     constructor(criteriaObject) {
+        const criteriaValidator = this.getCriteriaValidator();
         this.criteria = [];
 
-        const schema = {
-            properties: {},
-            definitions: {
-                simpleArray: { type: 'array' }
-            }
-        };
-        _.each(Criteria, (Criterion, key) => {
-            if (Criterion.prototype instanceof BaseCriterion) {
-                const criterionkey = key.replace(/Criterion$/, '');
-                schema.definitions[criterionkey] = Criteria[`${criterionkey}Schema`];
-                schema.properties[criterionkey] = {
-                    oneOf: [
-                        { $ref: '#/definitions/simpleArray' },
-                        { $ref: `#/definitions/${criterionkey}` }
-                    ]
-                };
-            }
-        });
-        const validator = new Ajv().compile(schema);
-        if (!validator(criteriaObject)) {
+        if (!criteriaValidator(criteriaObject)) {
             let message = '';
-            _.each(validator.errors, error => {
+            _.each(criteriaValidator.errors, error => {
                 message += `\noptions${error.dataPath} ${error.message}`;
             });
             throw new Error(message);
@@ -42,6 +24,39 @@ export class CriteriaEvaluator {
         });
     }
 
+    getCriteriaValidator() {
+        if (CriteriaEvaluator.validator) {
+            return CriteriaEvaluator.validator;
+        }
+
+        const schema = {
+            properties: {},
+            definitions: {}
+        };
+
+        _.each(Criteria, (Criterion, key) => {
+            if (Criterion.prototype instanceof BaseCriterion) {
+                const criterionkey = key.replace(/Criterion$/, '');
+                const criterionDefinition = `#/definitions/${criterionkey}`;
+
+                schema.definitions[criterionkey] = Criteria[`${criterionkey}Schema`];
+                schema.properties[criterionkey] = {
+                    oneOf: [
+                        { $ref: criterionDefinition },
+                        {
+                            type: 'array',
+                            items: {
+                                $ref: criterionDefinition
+                            }
+                        }
+                    ]
+                };
+            }
+        });
+        
+        return CriteriaEvaluator.validator = new Ajv().compile(schema);
+    }
+
     evaluate(data) {
         const nonconformity = [];
         this.criteria.forEach(criterion => {
diff --git a/Packages/ohif-measurements/client/conformance/criteria/MaxTargets.js b/Packages/ohif-measurements/client/conformance/criteria/MaxTargets.js
index 42617f297..1e26e5a79 100644
--- a/Packages/ohif-measurements/client/conformance/criteria/MaxTargets.js
+++ b/Packages/ohif-measurements/client/conformance/criteria/MaxTargets.js
@@ -2,6 +2,7 @@ import { BaseCriterion } from './BaseCriterion';
 import { _ } from 'meteor/underscore';
 
 export const MaxTargetsSchema = {
+    type: 'object',
     properties: {
         limit: {
             label: 'Max targets allowed in study',
diff --git a/Packages/ohif-measurements/client/conformance/criteria/MaxTargetsPerOrgan.js b/Packages/ohif-measurements/client/conformance/criteria/MaxTargetsPerOrgan.js
index b05e82078..311acdfac 100644
--- a/Packages/ohif-measurements/client/conformance/criteria/MaxTargetsPerOrgan.js
+++ b/Packages/ohif-measurements/client/conformance/criteria/MaxTargetsPerOrgan.js
@@ -1,6 +1,7 @@
 import { BaseCriterion } from './BaseCriterion';
 
 export const MaxTargetsPerOrganSchema = {
+    type: 'object',
     properties: {
         limit: {
             label: 'Max targets allowed per organ',
diff --git a/Packages/ohif-measurements/client/conformance/criteria/MeasurementsLength.js b/Packages/ohif-measurements/client/conformance/criteria/MeasurementsLength.js
index 5ef7af86f..50bd716f8 100644
--- a/Packages/ohif-measurements/client/conformance/criteria/MeasurementsLength.js
+++ b/Packages/ohif-measurements/client/conformance/criteria/MeasurementsLength.js
@@ -1,6 +1,7 @@
 import { BaseCriterion } from './BaseCriterion';
 
 export const MeasurementsLengthSchema = {
+    type: 'object',
     properties: {
         longAxis: {
             label: 'Minimum length of long axis',
diff --git a/Packages/ohif-measurements/client/conformance/criteria/Modality.js b/Packages/ohif-measurements/client/conformance/criteria/Modality.js
index 960c8cca3..c605072e4 100644
--- a/Packages/ohif-measurements/client/conformance/criteria/Modality.js
+++ b/Packages/ohif-measurements/client/conformance/criteria/Modality.js
@@ -2,6 +2,7 @@ import { BaseCriterion } from './BaseCriterion';
 import { _ } from 'meteor/underscore';
 
 export const ModalitySchema = {
+    type: 'object',
     properties: {
         method: {
             label: 'Specify if it\'s goinig to "allow" or "deny" the modalities',
diff --git a/Packages/ohif-measurements/client/conformance/criteria/NonTargetResponse.js b/Packages/ohif-measurements/client/conformance/criteria/NonTargetResponse.js
index 29378de90..fcd67ba70 100644
--- a/Packages/ohif-measurements/client/conformance/criteria/NonTargetResponse.js
+++ b/Packages/ohif-measurements/client/conformance/criteria/NonTargetResponse.js
@@ -1,6 +1,7 @@
 import { BaseCriterion } from './BaseCriterion';
 
 export const NonTargetResponseSchema = {
+    type: 'object'
 };
 
 /* NonTargetResponseCriterion
diff --git a/Packages/ohif-measurements/client/conformance/criteria/TargetType.js b/Packages/ohif-measurements/client/conformance/criteria/TargetType.js
index 40f227572..49cd7e022 100644
--- a/Packages/ohif-measurements/client/conformance/criteria/TargetType.js
+++ b/Packages/ohif-measurements/client/conformance/criteria/TargetType.js
@@ -1,6 +1,7 @@
 import { BaseCriterion } from './BaseCriterion';
 
 export const TargetTypeSchema = {
+    type: 'object'
 };
 
 /* TargetTypeCriterion