diff --git a/README.md b/README.md
index 32d77a87..f2eff1aa 100644
--- a/README.md
+++ b/README.md
@@ -321,7 +321,6 @@ The following tests are not yet implemented and therefore missing:
 - Mandatory Test 6.1.53
 - Mandatory Test 6.1.54
 - Mandatory Test 6.1.55
-- Mandatory Test 6.1.57
 - Mandatory Test 6.1.58
 - Mandatory Test 6.1.59
 
@@ -442,6 +441,7 @@ export const mandatoryTest_6_1_44: DocumentTest
 export const mandatoryTest_6_1_45: DocumentTest
 export const mandatoryTest_6_1_51: DocumentTest
 export const mandatoryTest_6_1_52: DocumentTest
+export const mandatoryTest_6_1_57: DocumentTest
 ```
 
 [(back to top)](#bsi-csaf-validator-lib)
diff --git a/csaf_2_1/mandatoryTests.js b/csaf_2_1/mandatoryTests.js
index c302572e..454b3ea1 100644
--- a/csaf_2_1/mandatoryTests.js
+++ b/csaf_2_1/mandatoryTests.js
@@ -64,3 +64,4 @@ export { mandatoryTest_6_1_44 } from './mandatoryTests/mandatoryTest_6_1_44.js'
 export { mandatoryTest_6_1_45 } from './mandatoryTests/mandatoryTest_6_1_45.js'
 export { mandatoryTest_6_1_51 } from './mandatoryTests/mandatoryTest_6_1_51.js'
 export { mandatoryTest_6_1_52 } from './mandatoryTests/mandatoryTest_6_1_52.js'
+export { mandatoryTest_6_1_57 } from './mandatoryTests/mandatoryTest_6_1_57.js'
diff --git a/csaf_2_1/mandatoryTests/mandatoryTest_6_1_57.js b/csaf_2_1/mandatoryTests/mandatoryTest_6_1_57.js
new file mode 100644
index 00000000..69281e7d
--- /dev/null
+++ b/csaf_2_1/mandatoryTests/mandatoryTest_6_1_57.js
@@ -0,0 +1,109 @@
+import Ajv from 'ajv/dist/jtd.js'
+
+const ajv = new Ajv()
+
+const branchSchema = /** @type {const} */ ({
+  additionalProperties: true,
+  optionalProperties: {
+    branches: {
+      elements: {
+        additionalProperties: true,
+        properties: {},
+      },
+    },
+  },
+})
+
+/*
+  This is the jtd schema that needs to match the input document so that the
+  test is activated. If this schema doesn't match it normally means that the input
+  document does not validate against the csaf json schema or optional fields that
+  the test checks are not present.
+ */
+const inputSchema = /** @type {const} */ ({
+  additionalProperties: true,
+  properties: {
+    product_tree: {
+      additionalProperties: true,
+      optionalProperties: {
+        branches: {
+          elements: branchSchema,
+        },
+      },
+    },
+  },
+})
+
+const validateInput = ajv.compile(inputSchema)
+const validateBranch = ajv.compile(branchSchema)
+
+/**
+ * This implements the mandatory test 6.1.57 of the CSAF 2.1 standard.
+ *
+ * @param {any} doc
+ */
+export function mandatoryTest_6_1_57(doc) {
+  const ctx = {
+    errors:
+      /** @type {Array<{ instancePath: string; message: string }>} */ ([]),
+    isValid: true,
+  }
+
+  if (!validateInput(doc)) {
+    return ctx
+  }
+
+  // Start the recursive check from the root branches
+  const branches = doc.product_tree?.branches ?? []
+  branches.forEach((branch, index) => {
+    checkBranch(branch, `/product_tree/branches/${index}`, [], ctx.errors)
+  })
+
+  if (ctx.errors.length > 0) {
+    ctx.isValid = false
+  }
+
+  return ctx
+}
+
+/**
+ * Validates a single branch and its nested branches recursively.
+ * Checks that no category (except product_family) appears more than once along the path.
+ *
+ * @param {any} branch
+ * @param {string} basePath
+ * @param {string[]} categoriesInPath
+ * @param {Array<{ instancePath: string; message: string }>} errors
+ */
+function checkBranch(branch, basePath, categoriesInPath, errors) {
+  const category = branch.category
+
+  if (category && category !== 'product_family') {
+    if (categoriesInPath.includes(category)) {
+      errors.push({
+        instancePath: `${basePath}/category`,
+        message: `Branch category "${category}" appears more than once along the path.`,
+      })
+    }
+  }
+
+  const newCategories =
+    category && category !== 'product_family'
+      ? [...categoriesInPath, category]
+      : categoriesInPath
+
+  // Recursively check nested branches
+  if (Array.isArray(branch.branches)) {
+    branch.branches.forEach(
+      (/** @type {any} */ childBranch, /** @type {number} */ index) => {
+        if (!validateBranch(childBranch)) return
+        checkBranch(
+          childBranch,
+          `${basePath}/branches/${index}`,
+          newCategories,
+          errors
+        )
+      }
+    )
+  }
+}
diff --git a/tests/csaf_2_1/mandatoryTest_6_1_57.js b/tests/csaf_2_1/mandatoryTest_6_1_57.js
new file mode 100644
index 00000000..853304c5
--- /dev/null
+++ b/tests/csaf_2_1/mandatoryTest_6_1_57.js
@@ -0,0 +1,49 @@
+import assert from 'node:assert'
+import { mandatoryTest_6_1_57 } from '../../csaf_2_1/mandatoryTests.js'
+
+describe('mandatoryTest_6_1_57', function () {
+  it('only runs on relevant documents', function () {
+    assert.equal(
+      mandatoryTest_6_1_57({ vulnerabilities: 'mydoc' }).errors.length,
+      0
+    )
+  })
+
+  it('passes when product_tree has no branches', function () {
+    assert.equal(
+      mandatoryTest_6_1_57({
+        product_tree: {
+          full_product_names: [
+            {
+              name: 'Example Company Controller A 1.0',
+              product_id: 'CSAFPID-908070601',
+            },
+          ],
+        },
+      }).errors.length,
+      0
+    )
+  })
+
+  it('skips recursion when an intermediate branch has invalid branches property', function () {
+    const result = mandatoryTest_6_1_57({
+      product_tree: {
+        branches: [
+          {
+            category: 'vendor',
+            name: 'Vendor A',
+            branches: [
+              {
+                category: 'product_name',
+                name: 'Product A',
+                branches: 'not-an-array',
+              },
+            ],
+          },
+        ],
+      },
+    })
+    assert.equal(result.errors.length, 0)
+    assert.equal(result.isValid, true)
+  })
+})
diff --git a/tests/csaf_2_1/oasis.js b/tests/csaf_2_1/oasis.js
index 8f223924..6a0f4903 100644
--- a/tests/csaf_2_1/oasis.js
+++ b/tests/csaf_2_1/oasis.js
@@ -28,7 +28,6 @@ const excluded = [
   '6.1.54',
   '6.1.55',
   '6.1.56',
-  '6.1.57',
   '6.1.58',
   '6.1.59',
   '6.2.11',