diff --git a/coder_sniffer/Drupal/Sniffs/Semantics/UnsilencedDeprecationSniff.php b/coder_sniffer/Drupal/Sniffs/Semantics/UnsilencedDeprecationSniff.php
new file mode 100644
index 00000000..f9b8dba0
--- /dev/null
+++ b/coder_sniffer/Drupal/Sniffs/Semantics/UnsilencedDeprecationSniff.php
@@ -0,0 +1,81 @@
+<?php
+/**
+ * \Drupal\Sniffs\Semantics\UnsilencedDeprecationSniff.
+ *
+ * @category PHP
+ * @package  PHP_CodeSniffer
+ * @link     http://pear.php.net/package/PHP_CodeSniffer
+ */
+
+namespace Drupal\Sniffs\Semantics;
+
+use PHP_CodeSniffer\Files\File;
+
+/**
+ * Checks that the trigger_error deprecation is silenced by a preceding '@'.
+ *
+ * @category PHP
+ * @package  PHP_CodeSniffer
+ * @link     http://pear.php.net/package/PHP_CodeSniffer
+ */
+class UnsilencedDeprecationSniff extends FunctionCall
+{
+
+
+    /**
+     * Returns an array of function names this test wants to listen for.
+     *
+     * @return array<string>
+     */
+    public function registerFunctionNames()
+    {
+        return ['trigger_error'];
+
+    }//end registerFunctionNames()
+
+
+    /**
+     * Processes this function call.
+     *
+     * @param \PHP_CodeSniffer\Files\File $phpcsFile    The file being scanned.
+     * @param int                         $stackPtr     The position of the function call in
+     *                                                  the stack.
+     * @param int                         $openBracket  The position of the opening
+     *                                                  parenthesis in the stack.
+     * @param int                         $closeBracket The position of the closing
+     *                                                  parenthesis in the stack.
+     *
+     * @return void
+     */
+    public function processFunctionCall(
+        file $phpcsFile,
+        $stackPtr,
+        $openBracket,
+        $closeBracket
+    ) {
+
+        $tokens   = $phpcsFile->getTokens();
+        $argument = $this->getArgument(2);
+
+        // If no second argument then quit.
+        if ($argument === false) {
+            return;
+        }
+
+        // Only check deprecation messages.
+        if (strcasecmp($tokens[$argument['start']]['content'], 'E_USER_DEPRECATED') !== 0) {
+            return;
+        }
+
+        if ($tokens[($stackPtr - 1)]['type'] !== 'T_ASPERAND') {
+            $error = 'All trigger_error calls used for deprecation must be prefixed by an "@"';
+            $fix   = $phpcsFile->addFixableError($error, $stackPtr, 'UnsilencedDeprecation');
+            if ($fix === true) {
+                $phpcsFile->fixer->addContentBefore($stackPtr, '@');
+            }
+        }
+
+    }//end processFunctionCall()
+
+
+}//end class
diff --git a/tests/Drupal/Semantics/UnsilencedDeprecationUnitTest.inc b/tests/Drupal/Semantics/UnsilencedDeprecationUnitTest.inc
new file mode 100644
index 00000000..1017fd6d
--- /dev/null
+++ b/tests/Drupal/Semantics/UnsilencedDeprecationUnitTest.inc
@@ -0,0 +1,19 @@
+<?php
+
+/**
+ * @file
+ * Test data for the relaxed version of FunctionUnsilencedDeprecationSniff coding standard.
+ */
+
+// No second parameter, so cannot fail it, both silenced and unsilenced.
+@trigger_error('CommentTestBase is deprecated in drupal 8.4.0');
+trigger_error('CommentTestBase is deprecated in drupal 8.4.0');
+
+// Not E_USER_DEPRECATED, so cannot fail it, both silenced and unsilenced.
+@trigger_error('CommentTestBase is deprecated in drupal 8.4.0', E_USER_SOMETHING_ELSE);
+trigger_error('CommentTestBase is deprecated in drupal 8.4.0', E_USER_SOMETHING_ELSE);
+
+// E_USER_DEPRECATED, so silenced is fine...
+@trigger_error('CommentTestBase is deprecated in drupal 8.4.0', E_USER_DEPRECATED);
+// ... but unsilenced fails.
+trigger_error('CommentTestBase is deprecated in drupal 8.4.0', E_USER_DEPRECATED);
diff --git a/tests/Drupal/Semantics/UnsilencedDeprecationUnitTest.inc.fixed b/tests/Drupal/Semantics/UnsilencedDeprecationUnitTest.inc.fixed
new file mode 100644
index 00000000..89aa4bc6
--- /dev/null
+++ b/tests/Drupal/Semantics/UnsilencedDeprecationUnitTest.inc.fixed
@@ -0,0 +1,19 @@
+<?php
+
+/**
+ * @file
+ * Test data for the relaxed version of FunctionUnsilencedDeprecationSniff coding standard.
+ */
+
+// No second parameter, so cannot fail it, both silenced and unsilenced.
+@trigger_error('CommentTestBase is deprecated in drupal 8.4.0');
+trigger_error('CommentTestBase is deprecated in drupal 8.4.0');
+
+// Not E_USER_DEPRECATED, so cannot fail it, both silenced and unsilenced.
+@trigger_error('CommentTestBase is deprecated in drupal 8.4.0', E_USER_SOMETHING_ELSE);
+trigger_error('CommentTestBase is deprecated in drupal 8.4.0', E_USER_SOMETHING_ELSE);
+
+// E_USER_DEPRECATED, so silenced is fine...
+@trigger_error('CommentTestBase is deprecated in drupal 8.4.0', E_USER_DEPRECATED);
+// ... but unsilenced fails.
+@trigger_error('CommentTestBase is deprecated in drupal 8.4.0', E_USER_DEPRECATED);
diff --git a/tests/Drupal/Semantics/UnsilencedDeprecationUnitTest.php b/tests/Drupal/Semantics/UnsilencedDeprecationUnitTest.php
new file mode 100644
index 00000000..fd99c54e
--- /dev/null
+++ b/tests/Drupal/Semantics/UnsilencedDeprecationUnitTest.php
@@ -0,0 +1,45 @@
+<?php
+
+namespace Drupal\Test\Semantics;
+
+use Drupal\Test\CoderSniffUnitTest;
+
+class UnsilencedDeprecationUnitTest extends CoderSniffUnitTest
+{
+
+
+    /**
+     * Returns the lines where errors should occur.
+     *
+     * The key of the array should represent the line number and the value
+     * should represent the number of errors that should occur on that line.
+     *
+     * @param string $testFile The name of the file being tested.
+     *
+     * @return array<int, int>
+     */
+    protected function getErrorList(string $testFile): array
+    {
+        return [19 => 1];
+
+    }//end getErrorList()
+
+
+    /**
+     * Returns the lines where warnings should occur.
+     *
+     * The key of the array should represent the line number and the value
+     * should represent the number of warnings that should occur on that line.
+     *
+     * @param string $testFile The name of the file being tested.
+     *
+     * @return array<int, int>
+     */
+    protected function getWarningList(string $testFile): array
+    {
+        return [];
+
+    }//end getWarningList()
+
+
+}//end class