diff --git a/.gitignore b/.gitignore
index a4b24e4553..a4967e344f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -21,3 +21,4 @@ node_modules
 
 # rule docs are generated
 docs/pages/pmd/rules
+.history/*
\ No newline at end of file
diff --git a/pmd-apex-6.49.0-SNAPSHOT.jar b/pmd-apex-6.49.0-SNAPSHOT.jar
deleted file mode 100644
index 82c0e96d43..0000000000
Binary files a/pmd-apex-6.49.0-SNAPSHOT.jar and /dev/null differ
diff --git a/pmd-apex/src/main/java/net/sourceforge/pmd/lang/apex/rule/bestpractices/ApexUnitTestClassShouldHaveRunAsRule.java b/pmd-apex/src/main/java/net/sourceforge/pmd/lang/apex/rule/bestpractices/ApexUnitTestClassShouldHaveRunAsRule.java
new file mode 100644
index 0000000000..4a403c50ee
--- /dev/null
+++ b/pmd-apex/src/main/java/net/sourceforge/pmd/lang/apex/rule/bestpractices/ApexUnitTestClassShouldHaveRunAsRule.java
@@ -0,0 +1,45 @@
+/**
+ * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
+ */
+
+package net.sourceforge.pmd.lang.apex.rule.bestpractices;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import net.sourceforge.pmd.lang.apex.ast.ASTBlockStatement;
+import net.sourceforge.pmd.lang.apex.ast.ASTMethod;
+import net.sourceforge.pmd.lang.apex.ast.ASTRunAsBlockStatement;
+import net.sourceforge.pmd.lang.apex.ast.ApexNode;
+import net.sourceforge.pmd.lang.apex.rule.AbstractApexUnitTestRule;
+
+/**
+ * Apex unit tests should have System.runAs methods in them
+ *
+ * @author t.prouvot
+ */
+public class ApexUnitTestClassShouldHaveRunAsRule extends AbstractApexUnitTestRule {
+
+    @Override
+    public Object visit(ASTMethod node, Object data) {
+        if (!isTestMethodOrClass(node)) {
+            return data;
+        }
+
+        return checkForRunAsStatements(node, data);
+    }
+
+    private Object checkForRunAsStatements(ApexNode<?> node, Object data) {
+        final List<ASTBlockStatement> blockStatements = node.findDescendantsOfType(ASTBlockStatement.class);
+        final List<ASTRunAsBlockStatement> runAsStatements = new ArrayList<>();
+
+        for (ASTBlockStatement blockStatement : blockStatements) {
+            runAsStatements.addAll(blockStatement.findDescendantsOfType(ASTRunAsBlockStatement.class));
+        }
+
+        if (!!runAsStatements.isEmpty()) {
+            addViolation(data, node);
+        }
+        return data;
+    }
+}
diff --git a/pmd-apex/src/main/resources/category/apex/bestpractices.xml b/pmd-apex/src/main/resources/category/apex/bestpractices.xml
index 84afa3c915..c54bb17323 100644
--- a/pmd-apex/src/main/resources/category/apex/bestpractices.xml
+++ b/pmd-apex/src/main/resources/category/apex/bestpractices.xml
@@ -64,6 +64,44 @@ public class Foo {
         </example>
     </rule>
 
+    <rule name="ApexUnitTestClassShouldHaveRunAs"
+          language="apex"
+          since="6.51.0"
+          message="Apex unit tests should use System.runAs() method"
+          class="net.sourceforge.pmd.lang.apex.rule.bestpractices.ApexUnitTestClassShouldHaveRunAsRule"
+          externalInfoUrl="${pmd.website.baseurl}/pmd_rules_apex_bestpractices.html#apexunittestclassshouldhaverunas">
+        <description>
+Apex unit tests should include at least one runAs method.  This makes the tests more robust, and independent from the 
+user running it.
+        </description>
+        <priority>3</priority>
+        <example>
+<![CDATA[
+@isTest
+private class TestRunAs {
+   public static testMethod void testRunAs() {
+        // Setup test data
+        // Create a unique UserName
+        String uniqueUserName = 'standarduser' + DateTime.now().getTime() + '@testorg.com';
+        // This code runs as the system user
+        Profile p = [SELECT Id FROM Profile WHERE Name='Standard User'];
+        User u = new User(Alias = 'standt', Email='standarduser@testorg.com',
+        EmailEncodingKey='UTF-8', LastName='Testing', LanguageLocaleKey='en_US',
+        LocaleSidKey='en_US', ProfileId = p.Id,
+        TimeZoneSidKey='America/Los_Angeles',
+         UserName=uniqueUserName);
+
+        System.runAs(u) {
+              // The following code runs as user 'u'
+              System.debug('Current User: ' + UserInfo.getUserName());
+              System.debug('Current Profile: ' + UserInfo.getProfileId());
+          }
+    }
+}
+]]>
+        </example>
+    </rule>
+
     <rule name="ApexUnitTestMethodShouldHaveIsTestAnnotation"
           since="6.13.0"
           language="apex"
diff --git a/pmd-apex/src/main/resources/rulesets/apex/apexunit.xml b/pmd-apex/src/main/resources/rulesets/apex/apexunit.xml
index efcca12aae..9c6547ef8a 100644
--- a/pmd-apex/src/main/resources/rulesets/apex/apexunit.xml
+++ b/pmd-apex/src/main/resources/rulesets/apex/apexunit.xml
@@ -9,6 +9,7 @@
     </description>
 
     <rule ref="category/apex/bestpractices.xml/ApexUnitTestClassShouldHaveAsserts" deprecated="true" />
+    <rule ref="category/apex/bestpractices.xml/ApexUnitTestClassShouldHaveRunAs" deprecated="true" />
     <rule ref="category/apex/bestpractices.xml/ApexUnitTestShouldNotUseSeeAllDataTrue" deprecated="true" />
 
 </ruleset>
diff --git a/pmd-apex/src/main/resources/rulesets/apex/quickstart.xml b/pmd-apex/src/main/resources/rulesets/apex/quickstart.xml
index 5fd3386416..2543193a41 100644
--- a/pmd-apex/src/main/resources/rulesets/apex/quickstart.xml
+++ b/pmd-apex/src/main/resources/rulesets/apex/quickstart.xml
@@ -250,6 +250,9 @@
          <property name="cc_block_highlighting" value="false" />
       </properties>
    </rule>
+   <rule ref="category/apex/bestpractices.xml/ApexUnitTestClassShouldHaveRunAs" message="Apex unit test classes should have at least one System.runAs() call">
+      <priority>3</priority>
+   </rule>
 <!--    <rule ref="category/apex/bestpractices.xml/ApexAssertionsShouldIncludeMessage"/> -->
 <!--    <rule ref="category/apex/bestpractices.xml/ApexUnitTestMethodShouldHaveIsTestAnnotation"/> -->
 <!--    <rule ref="category/apex/errorprone.xml/TestMethodsMustBeInTestClasses"/> -->
diff --git a/pmd-apex/src/test/java/net/sourceforge/pmd/lang/apex/rule/bestpractices/ApexUnitTestClassShouldHaveRunAsTest.java b/pmd-apex/src/test/java/net/sourceforge/pmd/lang/apex/rule/bestpractices/ApexUnitTestClassShouldHaveRunAsTest.java
new file mode 100644
index 0000000000..1c20e4ad7c
--- /dev/null
+++ b/pmd-apex/src/test/java/net/sourceforge/pmd/lang/apex/rule/bestpractices/ApexUnitTestClassShouldHaveRunAsTest.java
@@ -0,0 +1,11 @@
+/**
+ * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
+ */
+
+package net.sourceforge.pmd.lang.apex.rule.bestpractices;
+
+import net.sourceforge.pmd.testframework.PmdRuleTst;
+
+public class ApexUnitTestClassShouldHaveRunAsTest extends PmdRuleTst {
+    // no additional unit tests
+}
diff --git a/pmd-apex/src/test/resources/net/sourceforge/pmd/lang/apex/rule/bestpractices/xml/ApexUnitTestClassShouldHaveRunAs.xml b/pmd-apex/src/test/resources/net/sourceforge/pmd/lang/apex/rule/bestpractices/xml/ApexUnitTestClassShouldHaveRunAs.xml
new file mode 100644
index 0000000000..4eefe99873
--- /dev/null
+++ b/pmd-apex/src/test/resources/net/sourceforge/pmd/lang/apex/rule/bestpractices/xml/ApexUnitTestClassShouldHaveRunAs.xml
@@ -0,0 +1,99 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<test-data xmlns="http://pmd.sourceforge.net/rule-tests" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://pmd.sourceforge.net/rule-tests http://pmd.sourceforge.net/rule-tests_1_0_0.xsd">
+
+    <test-code>
+        <description>Problematic apex unit test - no runAs calls</description>
+        <expected-problems>1</expected-problems>
+        <code>
+            <![CDATA[
+@isTest
+private class TestRunAs {
+
+   public static testMethod void testNoRunAs() {
+
+      Profile p = [SELECT Id FROM Profile WHERE Name='Standard User'];
+      User u2 = new User(Alias = 'newUser', Email='newuser@testorg.com',
+         EmailEncodingKey='UTF-8', LastName='Testing', LanguageLocaleKey='en_US',
+         LocaleSidKey='en_US', ProfileId = p.Id,
+         TimeZoneSidKey='America/Los_Angeles', UserName='newuser@testorg.com');
+      System.debug('Current User: ' + UserInfo.getUserName());
+   }
+}
+        ]]>
+        </code>
+    </test-code>
+
+    <test-code>
+        <description>ApexUnitTestClassShouldHaveRunAs assumes APEX is case sensitive</description>
+        <expected-problems>0</expected-problems>
+        <code>
+            <![CDATA[
+@isTest
+private class TestRunAs {
+
+   @isTest
+   static void testIgnoreCase() {
+
+      Profile p = [SELECT Id FROM Profile WHERE Name='Standard User'];
+      User usr = new User(Alias = 'newUser', Email='newuser@testorg.com',
+         EmailEncodingKey='UTF-8', LastName='Testing', LanguageLocaleKey='en_US',
+         LocaleSidKey='en_US', ProfileId = p.Id,
+         TimeZoneSidKey='America/Los_Angeles', UserName='newuser@testorg.com');
+
+      SYSTEM.runAs(usr) {
+         System.debug('Current User: ' + UserInfo.getUserName());
+      }
+   }
+}
+     ]]>
+        </code>
+    </test-code>
+
+    <test-code>
+        <description>ApexUnitTestClassShouldHaveRunAs normal test case</description>
+        <expected-problems>0</expected-problems>
+        <code>
+            <![CDATA[
+@isTest
+private class TestRunAs {
+
+   public static testMethod void testIgnoreCase() {
+
+      Profile p = [SELECT Id FROM Profile WHERE Name='Standard User'];
+      User usr = new User(Alias = 'newUser', Email='newuser@testorg.com',
+         EmailEncodingKey='UTF-8', LastName='Testing', LanguageLocaleKey='en_US',
+         LocaleSidKey='en_US', ProfileId = p.Id,
+         TimeZoneSidKey='America/Los_Angeles', UserName='newuser@testorg.com');
+
+      System.runAs(usr) {
+         System.debug('Current User: ' + UserInfo.getUserName());
+      }
+   }
+}
+        ]]>
+        </code>
+    </test-code>
+
+    <test-code>
+        <description>ApexUnitTestClassShouldHaveRunAs: Verify use of custom class, negative test</description>
+        <expected-problems>2</expected-problems>
+        <expected-linenumbers>3,7</expected-linenumbers>
+        <code>
+            <![CDATA[
+@isTest
+public class RunAs {
+   public static testMethod void testRunAs() {
+      MyRunAs.runAs(someUser);
+   }
+
+   public static testMethod void testLocalVerify() {
+      verifyState();
+   }
+
+   private static void verifyState() {
+   }
+}
+        ]]>
+        </code>
+    </test-code>
+</test-data>
\ No newline at end of file
diff --git a/pmd-core/src/main/resources/rulesets/releases/6510.xml b/pmd-core/src/main/resources/rulesets/releases/6510.xml
new file mode 100644
index 0000000000..34f6df9363
--- /dev/null
+++ b/pmd-core/src/main/resources/rulesets/releases/6510.xml
@@ -0,0 +1,14 @@
+<?xml version="1.0"?>
+
+<ruleset name="6510"
+    xmlns="http://pmd.sourceforge.net/ruleset/2.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://pmd.sourceforge.net/ruleset/2.0.0 https://pmd.sourceforge.io/ruleset_2_0_0.xsd">
+  <description>
+This ruleset contains links to rules that are new in PMD v6.51.0
+  </description>
+
+    <rule ref="rulesets/apex/apexunit.xml/ApexUnitTestClassShouldHaveRunAs" />
+
+</ruleset>
+