diff --git a/backend/src/middleware/permissionsMiddleware.js b/backend/src/middleware/permissionsMiddleware.js
index 93096acba..bd5046331 100644
--- a/backend/src/middleware/permissionsMiddleware.js
+++ b/backend/src/middleware/permissionsMiddleware.js
@@ -10,7 +10,7 @@ const instance = neode()
 const isAuthenticated = rule({
   cache: 'contextual',
 })(async (_parent, _args, ctx, _info) => {
-  return ctx.user != null
+  return !!(ctx && ctx.user && ctx.user.id)
 })
 
 const isModerator = rule()(async (parent, args, { user }, info) => {
@@ -196,6 +196,7 @@ const permissions = shield(
       resetPassword: allow,
       AddPostEmotions: isAuthenticated,
       RemovePostEmotions: isAuthenticated,
+      block: isAuthenticated,
     },
     User: {
       email: isMyOwn,
diff --git a/backend/src/schema/resolvers/users.js b/backend/src/schema/resolvers/users.js
index b06f2d098..394f74e8e 100644
--- a/backend/src/schema/resolvers/users.js
+++ b/backend/src/schema/resolvers/users.js
@@ -8,16 +8,6 @@ const instance = neode()
 
 export default {
   Query: {
-    User: async (object, args, context, resolveInfo) => {
-      const { email } = args
-      if (email) {
-        const e = await instance.first('EmailAddress', { email })
-        let user = e.get('belongsTo')
-        user = await user.toJson()
-        return [user.node]
-      }
-      return neo4jgraphql(object, args, context, resolveInfo, false)
-    },
     blockedUsers: async (object, args, context, resolveInfo) => {
       try {
         const userModel = instance.model('User')
@@ -35,8 +25,27 @@ export default {
         throw new UserInputError(e.message)
       }
     },
+    User: async (object, args, context, resolveInfo) => {
+      const { email } = args
+      if (email) {
+        const e = await instance.first('EmailAddress', { email })
+        let user = e.get('belongsTo')
+        user = await user.toJson()
+        return [user.node]
+      }
+      return neo4jgraphql(object, args, context, resolveInfo, false)
+    },
   },
   Mutation: {
+    block: async (object, args, context, resolveInfo) => {
+      if(context.user.id === args.id) return null
+      const [user, blockedUser] = await Promise.all([
+        instance.find('User', context.user.id),
+        instance.find('User', args.id)
+      ])
+      await user.relateTo(blockedUser, 'blocked')
+      return blockedUser.toJson()
+    },
     UpdateUser: async (object, args, context, resolveInfo) => {
       args = await fileUpload(args, { file: 'avatarUpload', url: 'avatar' })
       try {
diff --git a/backend/src/schema/resolvers/users/blockedUsers.spec.js b/backend/src/schema/resolvers/users/blockedUsers.spec.js
index c77ed76d3..826ea649d 100644
--- a/backend/src/schema/resolvers/users/blockedUsers.spec.js
+++ b/backend/src/schema/resolvers/users/blockedUsers.spec.js
@@ -13,11 +13,15 @@ let blockedUser
 let server
 
 beforeEach(() => {
+  currentUser = undefined
   ;({ server } = createServer({
     context: () => {
       return {
         user: currentUser,
         driver,
+        cypherParams: {
+          currentUserId: currentUser ? currentUser.id : null,
+        },
       }
     },
   }))
@@ -59,7 +63,6 @@ describe('blockedUsers', () => {
       })
       await currentUser.relateTo(blockedUser, 'blocked')
       currentUser = await currentUser.toJson()
-      blockedUser = await blockedUser.toJson()
     })
 
     it('returns a list of blocked users', async () => {
@@ -82,14 +85,79 @@ describe('blockedUsers', () => {
 })
 
 describe('block', () => {
-  it.todo('throws permission error')
+  let blockAction
+
+  beforeEach(() => {
+    currentUser = undefined
+    blockAction = (variables) => {
+      const { mutate } = createTestClient(server)
+      const blockMutation = gql`mutation($id: ID!) {
+        block(id: $id) {
+          id
+          name
+          isBlocked
+        }
+      }`
+      return mutate({ mutation: blockMutation, variables })
+    }
+  })
+
+  it('throws permission error', async () => {
+    const result = await blockAction({ id: 'u2' })
+    expect(result.errors[0]).toHaveProperty('message', 'Not Authorised!')
+  })
 
   describe('authenticated', () => {
-    it.todo('throws argument error')
+    beforeEach(async () => {
+      currentUser = await instance.create('User', {
+        name: 'Current User',
+        id: 'u1',
+      })
+      currentUser = await currentUser.toJson()
+    })
+
+    describe('block yourself', () => {
+      it('returns null', async () => {
+        await expect(blockAction({ id: 'u1' }))
+          .resolves.toEqual(expect.objectContaining({ data: { block: null } }))
+      })
+    })
+
+    describe('block not existing user', () => {
+      it('returns null', async () => {
+        await expect(blockAction({ id: 'u2' }))
+          .resolves.toEqual(expect.objectContaining({ data: { block: null } }))
+      })
+    })
 
     describe('given a to-be-blocked user', () => {
-      it.todo('blocks a user')
-      it.todo('removes any `FOLLOW` relationship')
+      beforeEach(async () => {
+        blockedUser = await instance.create('User', {
+          name: 'Blocked User',
+          id: 'u2',
+        })
+      })
+
+      it('blocks a user', async () => {
+        await expect(blockAction({ id: 'u2' }))
+          .resolves.toEqual(expect.objectContaining({
+            data: { block: { id: 'u2', name: 'Blocked User', isBlocked: true} }
+          }))
+      })
+
+      it('unfollows the user', async () => {
+        const user = await instance.find('User', currentUser.id)
+        await user.relateTo(blockedUser, 'following')
+        const queryUser = gql`query { User(id: "u2") { id isBlocked followedByCurrentUser } }`
+        const { query } = createTestClient(server)
+        await expect(query({ query: queryUser })).resolves.toEqual(expect.objectContaining({
+          data: { User: [{id: "u2", isBlocked: false, followedByCurrentUser: true }] }
+        }))
+        await blockAction({id: 'u2'})
+        await expect(query({ query: queryUser })).resolves.toEqual(expect.objectContaining({
+          data: { User: [{id: "u2", isBlocked: true, followedByCurrentUser: false }] }
+        }))
+      })
 
       describe('blocked user writes a post', () => {
         it.todo('disappears in the newsfeed of the current user')