diff --git a/src/main/java/org/spdx/tools/ExitCode.java b/src/main/java/org/spdx/tools/ExitCode.java
new file mode 100644
index 0000000..98b8a3b
--- /dev/null
+++ b/src/main/java/org/spdx/tools/ExitCode.java
@@ -0,0 +1,43 @@
+/**
+ * SPDX-FileCopyrightText: 2026 SPDX Contributors
+ * SPDX-FileType: SOURCE
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package org.spdx.tools;
+
+/**
+ * Shared process exit status codes for the command line tools.
+ * <br/>
+ * Individual tools are free to only use a subset of these - e.g. a tool
+ * with no document-level validity concept may only ever return
+ * {@link #SUCCESS} or {@link #ERROR}.
+ * <br/>
+ * Values match the {@code CommandLine.ExitCode} constants used by
+ * <a href="https://picocli.info/">picocli</a>, a common Java CLI framework 
+ * ({@code OK=0}, {@code SOFTWARE=1}, {@code USAGE=2}).
+ *
+ * @author Arthit Suriyawongkul
+ */
+public class ExitCode {
+
+	private ExitCode() {
+		// Static constants only, no instances
+	}
+
+	/**
+	 * The command completed successfully.
+	 */
+	public static final int SUCCESS = 0;
+
+	/**
+	 * The command failed - e.g. the SPDX document is invalid, or could
+	 * not be read/parsed.
+	 */
+	public static final int ERROR = 1;
+
+	/**
+	 * The command was invoked incorrectly - e.g. missing or invalid
+	 * arguments.
+	 */
+	public static final int USAGE_ERROR = 2;
+}
diff --git a/src/main/java/org/spdx/tools/Verify.java b/src/main/java/org/spdx/tools/Verify.java
index 00ff30e..64056b7 100644
--- a/src/main/java/org/spdx/tools/Verify.java
+++ b/src/main/java/org/spdx/tools/Verify.java
@@ -48,27 +48,47 @@
 
 /**
  * Verifies an SPDX document and lists any verification errors
+ * <br/>
+ * Exit codes:
+ * <ul>
+ *   <li>0 - the SPDX document is valid</li>
+ *   <li>1 - the SPDX document is invalid, or could not be read/parsed</li>
+ *   <li>2 - the command was invoked incorrectly (missing/invalid arguments)</li>
+ * </ul>
  * @author Gary O'Neall
  */
 public class Verify {
 
 	static final int MIN_ARGS = 1;
 	static final int MAX_ARGS = 2;
-	static final int ERROR_STATUS = 1;
+
 	public static final String JSON_SCHEMA_RESOURCE_V2_3 = "resources/spdx-schema-v2.3.json";
 	public static final String JSON_SCHEMA_RESOURCE_V2_2 = "resources/spdx-schema-v2.2.json";
 	public static final String JSON_SCHEMA_RESOURCE_V3 = "resources/spdx-schema-v3.0.1.json";
-	
+
 	static final ObjectMapper JSON_MAPPER = new ObjectMapper().enable(SerializationFeature.INDENT_OUTPUT);
-	
+
 	/**
+	 * Main entry point for the Verify tool
+	 *
 	 * @param args args[0] SPDX file path; args[1] [RDFXML|JSON|XLS|XLSX|YAML|TAG] an optional file type - if not present, file type of the to file will be used
 	 */
 	public static void main(String[] args) {
+		System.exit(run(args));
+	}
+
+	/**
+	 * Runs the Verify command logic and reports results to standard out/error,
+	 * without terminating the JVM - allows the logic to be unit tested.
+	 *
+	 * @param args args[0] SPDX file path; args[1] [RDFXML|JSON|XLS|XLSX|YAML|TAG] an optional file type - if not present, file type of the to file will be used
+	 * @return process exit status, see {@link ExitCode}
+	 */
+	static int run(String[] args) {
 		if (args.length < MIN_ARGS) {
 			System.err
 					.println("Usage:\n Verify file\nwhere file is the file path to an SPDX file");
-			System.exit(ERROR_STATUS);
+			return ExitCode.USAGE_ERROR;
 		}
 		if (args.length > MAX_ARGS) {
 			System.out.println("Warning: Extra arguments will be ignored");
@@ -82,7 +102,7 @@ public static void main(String[] args) {
 					fileType = SpdxToolsHelper.strToFileType(args[1]);
 				} catch (Exception ex) {
 					System.err.println("Invalid file type: "+args[1]);
-					System.exit(ERROR_STATUS);
+					return ExitCode.USAGE_ERROR;
 				}
 			} else {
 				fileType = SpdxToolsHelper.fileToFileType(new File(args[0]));
@@ -90,10 +110,10 @@ public static void main(String[] args) {
 			verify = verify(args[0], fileType);
 		} catch (SpdxVerificationException e) {
 			System.out.println(e.getMessage());
-			System.exit(ERROR_STATUS);
+			return ExitCode.ERROR;
 		} catch (InvalidFileNameException e) {
 			System.err.println("Invalid file name: "+args[0]);
-			System.exit(ERROR_STATUS);
+			return ExitCode.USAGE_ERROR;
 		}
 		// separate out the warning from errors
 		List<String> warnings = new ArrayList<>();
@@ -120,8 +140,9 @@ public static void main(String[] args) {
 		}
 		if (errors.isEmpty()) {
 			System.out.println("This SPDX Document is valid.");
+			return ExitCode.SUCCESS;
 		} else {
-			System.exit(ERROR_STATUS);
+			return ExitCode.ERROR;
 		}
 	}