All, I am using JAXB classes as my model objects that are getting passed into the rules engine. I get the exception below. Here is how I am loading the rules and adding the objects into working memory: try { builder = new PackageBuilder(); builder.addPackageFromDrl( new InputStreamReader( RtvDecisionEngine.class.getResourceAsStream("rtv.drl" ) ) ); builder.addPackageFromDrl ( new InputStreamReader( RtvDecisionEngine.class.getResourceAsStream(" modelDiscrepancyRules.drl" ) ) ); ruleBase = RuleBaseFactory.newRuleBase(); ruleBase.addPackage ( builder.getPackage() ); } catch(Exception e) { throw new RuntimeException("Failure loading the Rules", e); } final StatefulSession session = ruleBase.newStatefulSession(); DetailLine line = rtvLines[i]; session.insert(line); Ron --------------------------------------------------- Exception --------------------------------------------------- Exception in thread "main" java.lang.VerifyError: class com.circuitcity.rtvcrms.impl.DetailLineDocumentImpl$DetailLineImplShadowProxyoverrides final method . at java.lang.ClassLoader.defineClass1 (Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:620) at java.lang.ClassLoader.defineClass(ClassLoader.java:465) at org.drools.rule.MapBackedClassLoader.fastFindClass( MapBackedClassLoader.java :40) at org.drools.rule.MapBackedClassLoader.loadClass( MapBackedClassLoader.java:59) at java.lang.ClassLoader.loadClass(ClassLoader.java:251) at org.drools.reteoo.Rete$ObjectTypeConf.<init>(Rete.java :352) at org.drools.reteoo.Rete.assertObject(Rete.java:152) at org.drools.reteoo.ReteooRuleBase.assertObject(ReteooRuleBase.java :190) at org.drools.reteoo.ReteooWorkingMemory.doInsert( ReteooWorkingMemory.java :70) at org.drools.common.AbstractWorkingMemory.insert( AbstractWorkingMemory.java:772) at org.drools.common.AbstractWorkingMemory.insert( AbstractWorkingMemory.java:584) at com.circuitcity.rtvcrms.rules.RtvDecisionEngine.processDetailLines( RtvDecisionEngine.java:95) at com.circuitcity.rtvcrms.rules.RtvDecisionEngine.executeRules( RtvDecisionEngine.java:64) at com.circuitcity.rtvcrms.test.MainBasedTester.main( MainBasedTester.java:34)