diff --git a/src/logic/logic.ts b/src/logic/logic.ts
index 9f66b23f6..f42532940 100644
--- a/src/logic/logic.ts
+++ b/src/logic/logic.ts
@@ -3,10 +3,12 @@
  * Utilities for working with program bytes.
  */
 
+/** @deprecated langspec.json is deprecated aross all SDKs */
 import langspec from './langspec.json';
 
 /**
  * Langspec Op Structure
+ * @deprecated for langspec.json is deprecated aross all SDKs
  */
 interface OpStructure {
   Opcode: number;
@@ -23,13 +25,17 @@ interface OpStructure {
   Groups: string[];
 }
 
+/** @deprecated for langspec.json is deprecated aross all SDKs */
 let opcodes: {
   [key: number]: OpStructure;
 };
 
+/** @deprecated for langspec.json is deprecated aross all SDKs */
 const maxCost = 20000;
+/** @deprecated for langspec.json is deprecated aross all SDKs */
 const maxLength = 1000;
 
+/** @deprecated for langspec.json is deprecated aross all SDKs */
 export function parseUvarint(
   array: Uint8Array
 ): [numberFound: number, size: number] {
@@ -49,6 +55,7 @@ export function parseUvarint(
   return [0, 0];
 }
 
+/** @deprecated for langspec.json is deprecated aross all SDKs */
 function readIntConstBlock(
   program: Uint8Array,
   pc: number
@@ -79,6 +86,7 @@ function readIntConstBlock(
   return [size, ints];
 }
 
+/** @deprecated for langspec.json is deprecated aross all SDKs */
 function readByteConstBlock(
   program: Uint8Array,
   pc: number
@@ -116,6 +124,7 @@ function readByteConstBlock(
   return [size, byteArrays];
 }
 
+/** @deprecated for langspec.json is deprecated aross all SDKs */
 function readPushIntOp(
   program: Uint8Array,
   pc: number
@@ -129,6 +138,7 @@ function readPushIntOp(
   return [size, numberFound];
 }
 
+/** @deprecated for langspec.json is deprecated aross all SDKs */
 function readPushByteOp(
   program: Uint8Array,
   pc: number
@@ -151,6 +161,12 @@ function readPushByteOp(
 
 /** readProgram validates program for length and running cost,
  * and additionally provides the found int variables and byte blocks
+ *
+ * @deprecated Validation relies on metadata (`langspec.json`) that
+ * does not accurately represent opcode behavior across program versions.
+ * The behavior of `readProgram` relies on `langspec.json`.
+ * Thus, this method is being deprecated.
+ *
  * @param program - Program to check
  * @param args - Program arguments as array of Uint8Array arrays
  * @throws
@@ -254,6 +270,12 @@ export function readProgram(
 
 /**
  * checkProgram validates program for length and running cost
+ *
+ * @deprecated Validation relies on metadata (`langspec.json`) that
+ * does not accurately represent opcode behavior across program versions.
+ * The behavior of `checkProgram` relies on `langspec.json`.
+ * Thus, this method is being deprecated.
+ *
  * @param program - Program to check
  * @param args - Program arguments as array of Uint8Array arrays
  * @throws
@@ -264,25 +286,31 @@ export function checkProgram(program: Uint8Array, args?: Uint8Array[]) {
   return success;
 }
 
+/** @deprecated for langspec.json is deprecated aross all SDKs */
 export function checkIntConstBlock(program: Uint8Array, pc: number) {
   const [size] = readIntConstBlock(program, pc);
   return size;
 }
 
+/** @deprecated for langspec.json is deprecated aross all SDKs */
 export function checkByteConstBlock(program: Uint8Array, pc: number) {
   const [size] = readByteConstBlock(program, pc);
   return size;
 }
 
+/** @deprecated for langspec.json is deprecated aross all SDKs */
 export function checkPushIntOp(program: Uint8Array, pc: number) {
   const [size] = readPushIntOp(program, pc);
   return size;
 }
 
+/** @deprecated for langspec.json is deprecated aross all SDKs */
 export function checkPushByteOp(program: Uint8Array, pc: number) {
   const [size] = readPushByteOp(program, pc);
   return size;
 }
 
+/** @deprecated for langspec.json is deprecated aross all SDKs */
 export const langspecEvalMaxVersion = langspec.EvalMaxVersion;
+/** @deprecated for langspec.json is deprecated aross all SDKs */
 export const langspecLogicSigVersion = langspec.LogicSigVersion;
diff --git a/src/logicsig.ts b/src/logicsig.ts
index 4904d3c52..74c0e0bef 100644
--- a/src/logicsig.ts
+++ b/src/logicsig.ts
@@ -1,10 +1,10 @@
 import * as nacl from './nacl/naclWrappers';
 import * as address from './encoding/address';
 import * as encoding from './encoding/encoding';
-import * as logic from './logic/logic';
 import { verifyMultisig } from './multisig';
 import * as utils from './utils/utils';
 import * as txnBuilder from './transaction';
+import { isValidAddress } from './encoding/address';
 import {
   EncodedLogicSig,
   EncodedLogicSigAccount,
@@ -20,6 +20,38 @@ interface LogicSigStorageStructure {
   msig?: EncodedMultisig;
 }
 
+/** sanityCheckProgram performs heuristic program validation:
+ * check if passed in bytes are Algorand address or is B64 encoded, rather than Teal bytes
+ *
+ * @param program - Program bytes to check
+ */
+export function sanityCheckProgram(program: Uint8Array) {
+  if (!program || program.length === 0) throw new Error('empty program');
+
+  const lineBreakOrd = '\n'.charCodeAt(0);
+  const blankSpaceOrd = ' '.charCodeAt(0);
+  const tildeOrd = '~'.charCodeAt(0);
+
+  const isPrintable = (x: number) => blankSpaceOrd <= x && x <= tildeOrd;
+  const isAsciiPrintable = program.every(
+    (x: number) => x === lineBreakOrd || isPrintable(x)
+  );
+
+  if (isAsciiPrintable) {
+    const programStr = Buffer.from(program).toString();
+
+    if (isValidAddress(programStr))
+      throw new Error('requesting program bytes, get Algorand address');
+
+    if (Buffer.from(programStr, 'base64').toString('base64') === programStr)
+      throw new Error('program should not be b64 encoded');
+
+    throw new Error(
+      'program bytes are all ASCII printable characters, not looking like Teal byte code'
+    );
+  }
+}
+
 /**
  LogicSig implementation
  */
@@ -49,9 +81,7 @@ export class LogicSig implements LogicSigStorageStructure {
     if (programArgs != null)
       args = programArgs.map((arg) => new Uint8Array(arg));
 
-    if (!logic.checkProgram(program, args)) {
-      throw new Error('Invalid program');
-    }
+    sanityCheckProgram(program);
 
     this.logic = program;
     this.args = args;
@@ -93,7 +123,7 @@ export class LogicSig implements LogicSigStorageStructure {
     }
 
     try {
-      logic.checkProgram(this.logic, this.args);
+      sanityCheckProgram(this.logic);
     } catch (e) {
       return false;
     }
diff --git a/tests/7.AlgoSDK.js b/tests/7.AlgoSDK.js
index e831786b9..6cc0c67ee 100644
--- a/tests/7.AlgoSDK.js
+++ b/tests/7.AlgoSDK.js
@@ -830,11 +830,6 @@ describe('Algosdk (AKA end to end)', () => {
       assert.equal(lsig.logic, program);
       assert.deepEqual(lsig.args, args);
     });
-    it('should throw on invalid program', () => {
-      const program = Uint8Array.from([1, 32, 1, 1, 34]);
-      program[0] = 128;
-      assert.throws(() => algosdk.makeLogicSig(program));
-    });
   });
   describe('Single logic sig', () => {
     it('should work on valid program', () => {
diff --git a/tests/8.LogicSig.ts b/tests/8.LogicSig.ts
index e7e7a5fba..08be74abf 100644
--- a/tests/8.LogicSig.ts
+++ b/tests/8.LogicSig.ts
@@ -65,11 +65,6 @@ describe('LogicSig', () => {
       const verified = lsig.verify(pk);
       assert.strictEqual(verified, false);
     });
-    it('should fail on invalid program', () => {
-      const program = Uint8Array.from([1, 32, 1, 1, 34]);
-      program[0] = 128;
-      assert.throws(() => algosdk.makeLogicSig(program));
-    });
   });
 
   describe('address', () => {
@@ -129,11 +124,6 @@ describe('LogicSigAccount', () => {
       const decoded = algosdk.LogicSigAccount.fromByte(encoded);
       assert.deepStrictEqual(decoded, lsigAccount);
     });
-    it('should fail on invalid program', () => {
-      const program = Uint8Array.from([1, 32, 1, 1, 34]);
-      program[0] = 128;
-      assert.throws(() => new algosdk.LogicSigAccount(program));
-    });
   });
 
   describe('sign', () => {
diff --git a/tests/cucumber/steps/steps.js b/tests/cucumber/steps/steps.js
index 9f8cbb6df..dabaa82f6 100644
--- a/tests/cucumber/steps/steps.js
+++ b/tests/cucumber/steps/steps.js
@@ -4454,6 +4454,32 @@ module.exports = function getSteps(options) {
     }
   );
 
+  Given(
+    'a base64 encoded program bytes for heuristic sanity check {string}',
+    async function (programByteStr) {
+      this.seeminglyProgram = new Uint8Array(
+        Buffer.from(programByteStr, 'base64')
+      );
+    }
+  );
+
+  When('I start heuristic sanity check over the bytes', async function () {
+    this.actualErrMsg = undefined;
+    try {
+      new algosdk.LogicSigAccount(this.seeminglyProgram); // eslint-disable-line
+    } catch (e) {
+      this.actualErrMsg = e.message;
+    }
+  });
+
+  Then(
+    'if the heuristic sanity check throws an error, the error contains {string}',
+    async function (errMsg) {
+      if (errMsg !== '') assert.ok(this.actualErrMsg.includes(errMsg));
+      else assert.strictEqual(this.actualErrMsg, undefined);
+    }
+  );
+
   if (!options.ignoreReturn) {
     return steps;
   }
diff --git a/tests/cucumber/unit.tags b/tests/cucumber/unit.tags
index ca26f899b..4062eadb6 100644
--- a/tests/cucumber/unit.tags
+++ b/tests/cucumber/unit.tags
@@ -11,6 +11,7 @@
 @unit.indexer.ledger_refactoring
 @unit.indexer.logs
 @unit.offline
+@unit.program_sanity_check
 @unit.rekey
 @unit.responses
 @unit.responses.231