diff --git a/internal/relationtuple/transact_server.go b/internal/relationtuple/transact_server.go
index 1e08332a2..b84dd92e3 100644
--- a/internal/relationtuple/transact_server.go
+++ b/internal/relationtuple/transact_server.go
@@ -8,6 +8,7 @@ import (
 	"encoding/json"
 	"net/http"
 
+	"github.com/ory/keto/internal/x/validate"
 	"github.com/ory/keto/ketoapi"
 
 	rts "github.com/ory/keto/proto/ory/keto/relation_tuples/v1alpha2"
@@ -175,6 +176,15 @@ func (h *handler) createRelation(w http.ResponseWriter, r *http.Request, _ httpr
 func (h *handler) deleteRelations(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
 	ctx := r.Context()
 
+	if err := validate.All(r,
+		validate.NoExtraQueryParams(ketoapi.RelationQueryKeys...),
+		validate.QueryParamsContainsOneOf(ketoapi.NamespaceKey),
+		validate.HasEmptyBody(),
+	); err != nil {
+		h.d.Writer().WriteError(w, r, err)
+		return
+	}
+
 	q := r.URL.Query()
 	query, err := (&ketoapi.RelationQuery{}).FromURLQuery(q)
 	if err != nil {
diff --git a/internal/relationtuple/transact_server_test.go b/internal/relationtuple/transact_server_test.go
index a8ed8cf5a..86f6839c2 100644
--- a/internal/relationtuple/transact_server_test.go
+++ b/internal/relationtuple/transact_server_test.go
@@ -11,23 +11,20 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"net/url"
+	"strings"
 	"testing"
 
+	"github.com/julienschmidt/httprouter"
 	"github.com/ory/x/pointerx"
-
-	"github.com/ory/keto/ketoapi"
-
-	"github.com/ory/keto/internal/driver/config"
-
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
-	"github.com/julienschmidt/httprouter"
-
 	"github.com/ory/keto/internal/driver"
+	"github.com/ory/keto/internal/driver/config"
 	"github.com/ory/keto/internal/namespace"
 	"github.com/ory/keto/internal/relationtuple"
 	"github.com/ory/keto/internal/x"
+	"github.com/ory/keto/ketoapi"
 )
 
 func TestWriteHandlers(t *testing.T) {
@@ -218,6 +215,85 @@ func TestWriteHandlers(t *testing.T) {
 			require.NoError(t, err)
 			assert.Equal(t, []*relationtuple.RelationTuple{}, actualRTs)
 		})
+
+		t.Run("suite=bad requests", func(t *testing.T) {
+			nspace := addNamespace(t)
+
+			rts := []*ketoapi.RelationTuple{
+				{
+					Namespace: nspace.Name,
+					Object:    "deleted obj",
+					Relation:  "deleted rel",
+					SubjectID: pointerx.Ptr("deleted subj 1"),
+				},
+				{
+					Namespace: nspace.Name,
+					Object:    "deleted obj",
+					Relation:  "deleted rel",
+					SubjectID: pointerx.Ptr("deleted subj 2"),
+				},
+			}
+
+			relationtuple.MapAndWriteTuples(t, reg, rts...)
+
+			assertBadRequest := func(t *testing.T, req *http.Request) {
+				resp, err := ts.Client().Do(req)
+				require.NoError(t, err)
+				assert.Equal(t, http.StatusBadRequest, resp.StatusCode)
+			}
+
+			assertTuplesExist := func(t *testing.T) {
+				mappedQuery, err := reg.Mapper().FromQuery(ctx, &ketoapi.RelationQuery{
+					Namespace: &nspace.Name,
+				})
+				require.NoError(t, err)
+
+				actualRTs, _, err := reg.RelationTupleManager().GetRelationTuples(ctx, mappedQuery, x.WithSize(10))
+				require.NoError(t, err)
+				mappedRTs, err := reg.Mapper().ToTuple(ctx, actualRTs...)
+				require.NoError(t, err)
+				assert.ElementsMatch(t, rts, mappedRTs)
+			}
+
+			t.Run("case=bad request if body sent", func(t *testing.T) {
+				q := url.Values{
+					"namespace": {nspace.Name},
+					"object":    {"deleted obj"},
+					"relation":  {"deleted rel"},
+				}
+				req, err := http.NewRequest(
+					http.MethodDelete,
+					ts.URL+relationtuple.WriteRouteBase+"?"+q.Encode(),
+					strings.NewReader("some body"))
+				require.NoError(t, err)
+
+				assertBadRequest(t, req)
+				assertTuplesExist(t)
+			})
+
+			t.Run("case=bad request query param misspelled", func(t *testing.T) {
+				req, err := http.NewRequest(
+					http.MethodDelete,
+					ts.URL+relationtuple.WriteRouteBase+"?invalid=param",
+					nil)
+				require.NoError(t, err)
+
+				assertBadRequest(t, req)
+				assertTuplesExist(t)
+			})
+
+			t.Run("case=bad request if query params misssing", func(t *testing.T) {
+				req, err := http.NewRequest(
+					http.MethodDelete,
+					ts.URL+relationtuple.WriteRouteBase,
+					nil)
+				require.NoError(t, err)
+
+				assertBadRequest(t, req)
+				assertTuplesExist(t)
+			})
+		})
+
 	})
 
 	t.Run("method=patch", func(t *testing.T) {
diff --git a/internal/x/validate/validate.go b/internal/x/validate/validate.go
new file mode 100644
index 000000000..e29993ac1
--- /dev/null
+++ b/internal/x/validate/validate.go
@@ -0,0 +1,75 @@
+// Copyright © 2023 Ory Corp
+// SPDX-License-Identifier: Apache-2.0
+
+package validate
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+
+	"github.com/ory/herodot"
+)
+
+type Validator func(r *http.Request) (ok bool, reason string)
+
+// All runs all validators and returns an error if any of them fail. It returns
+// a ErrBadRequest with all failed validation messages.
+func All(r *http.Request, validator ...Validator) error {
+	var reasons []string
+	for _, v := range validator {
+		if ok, msg := v(r); !ok {
+			reasons = append(reasons, msg)
+		}
+	}
+	if len(reasons) > 0 {
+		return herodot.ErrBadRequest.WithReason(strings.Join(reasons, "; "))
+	}
+	return nil
+}
+
+// NoExtraQueryParams returns a validator that checks if the request has any
+// query parameters that are not in the except list.
+func NoExtraQueryParams(except ...string) Validator {
+	return func(req *http.Request) (ok bool, reason string) {
+		allowed := make(map[string]struct{}, len(except))
+		for _, e := range except {
+			allowed[e] = struct{}{}
+		}
+		for key := range req.URL.Query() {
+			if _, found := allowed[key]; !found {
+				return false, fmt.Sprintf("query parameter key %q unknown", key)
+			}
+		}
+		return true, ""
+	}
+}
+
+// QueryParamsContainsOneOf returns a validator that checks if the request has
+// at least one of the specified query parameters.
+func QueryParamsContainsOneOf(keys ...string) Validator {
+	return func(req *http.Request) (ok bool, reason string) {
+		oneOfKeys := make(map[string]struct{}, len(keys))
+		for _, k := range keys {
+			oneOfKeys[k] = struct{}{}
+		}
+		for key := range req.URL.Query() {
+			if _, found := oneOfKeys[key]; found {
+				return true, ""
+			}
+		}
+		return false, fmt.Sprintf("quey parameters must specify at least one of the following: %s", strings.Join(keys, ", "))
+	}
+}
+
+// HasEmptyBody returns a validator that checks if the request body is empty.
+func HasEmptyBody() Validator {
+	return func(r *http.Request) (ok bool, reason string) {
+		_, err := r.Body.Read([]byte{})
+		if err != io.EOF {
+			return false, "body is not empty"
+		}
+		return true, ""
+	}
+}
diff --git a/internal/x/validate/validate_test.go b/internal/x/validate/validate_test.go
new file mode 100644
index 000000000..50ff5d8f7
--- /dev/null
+++ b/internal/x/validate/validate_test.go
@@ -0,0 +1,116 @@
+// Copyright © 2023 Ory Corp
+// SPDX-License-Identifier: Apache-2.0
+
+package validate_test
+
+import (
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/ory/keto/internal/x/validate"
+)
+
+func toURL(t *testing.T, s string) *url.URL {
+	u, err := url.Parse(s)
+	require.NoError(t, err)
+	return u
+}
+
+func TestValidateNoExtraParams(t *testing.T) {
+	for _, tt := range []struct {
+		name      string
+		req       *http.Request
+		assertErr assert.ErrorAssertionFunc
+	}{
+		{
+			name:      "empty",
+			req:       &http.Request{URL: toURL(t, "https://example.com")},
+			assertErr: assert.NoError,
+		},
+		{
+			name:      "all params",
+			req:       &http.Request{URL: toURL(t, "https://example.com?foo=1&bar=baz")},
+			assertErr: assert.NoError,
+		},
+		{
+			name:      "extra params",
+			req:       &http.Request{URL: toURL(t, "https://example.com?foo=1&bar=2&baz=3")},
+			assertErr: assert.Error,
+		},
+	} {
+		t.Run("case="+tt.name, func(t *testing.T) {
+			err := validate.All(tt.req, validate.NoExtraQueryParams("foo", "bar"))
+			tt.assertErr(t, err)
+		})
+	}
+}
+
+func TestQueryParamsContainsOneOf(t *testing.T) {
+	for _, tt := range []struct {
+		name      string
+		req       *http.Request
+		assertErr assert.ErrorAssertionFunc
+	}{
+		{
+			name:      "empty",
+			req:       &http.Request{URL: toURL(t, "https://example.com")},
+			assertErr: assert.Error,
+		},
+		{
+			name:      "other",
+			req:       &http.Request{URL: toURL(t, "https://example.com?a=1&b=2&c=3")},
+			assertErr: assert.Error,
+		},
+		{
+			name:      "one",
+			req:       &http.Request{URL: toURL(t, "https://example.com?foo=1")},
+			assertErr: assert.NoError,
+		},
+		{
+			name:      "all params",
+			req:       &http.Request{URL: toURL(t, "https://example.com?foo=1&bar=baz")},
+			assertErr: assert.NoError,
+		},
+		{
+			name:      "extra params",
+			req:       &http.Request{URL: toURL(t, "https://example.com?foo=1&bar=2&baz=3")},
+			assertErr: assert.NoError,
+		},
+	} {
+		t.Run("case="+tt.name, func(t *testing.T) {
+			err := validate.All(tt.req, validate.QueryParamsContainsOneOf("foo", "bar"))
+			tt.assertErr(t, err)
+		})
+	}
+}
+
+func TestValidateHasEmptyBody(t *testing.T) {
+	for _, tt := range []struct {
+		name      string
+		req       *http.Request
+		assertErr assert.ErrorAssertionFunc
+	}{
+		{
+			name:      "empty body",
+			req:       &http.Request{Body: io.NopCloser(strings.NewReader(""))},
+			assertErr: assert.NoError,
+		},
+		{
+			name:      "non-empty body",
+			req:       &http.Request{Body: io.NopCloser(strings.NewReader("content"))},
+			assertErr: assert.Error,
+		},
+	} {
+		t.Run("case="+tt.name, func(t *testing.T) {
+			err := validate.All(tt.req, validate.HasEmptyBody())
+			tt.assertErr(t, err)
+		})
+	}
+
+}
diff --git a/ketoapi/enc_url_query.go b/ketoapi/enc_url_query.go
index 0001c391a..98e397a24 100644
--- a/ketoapi/enc_url_query.go
+++ b/ketoapi/enc_url_query.go
@@ -40,14 +40,14 @@ func (q *RelationQuery) FromURLQuery(query url.Values) (*RelationQuery, error) {
 		return nil, ErrIncompleteSubject
 	}
 
-	if query.Has("namespace") {
-		q.Namespace = pointerx.Ptr(query.Get("namespace"))
+	if query.Has(NamespaceKey) {
+		q.Namespace = pointerx.Ptr(query.Get(NamespaceKey))
 	}
-	if query.Has("object") {
-		q.Object = pointerx.Ptr(query.Get("object"))
+	if query.Has(ObjectKey) {
+		q.Object = pointerx.Ptr(query.Get(ObjectKey))
 	}
-	if query.Has("relation") {
-		q.Relation = pointerx.Ptr(query.Get("relation"))
+	if query.Has(RelationKey) {
+		q.Relation = pointerx.Ptr(query.Get(RelationKey))
 	}
 
 	return q, nil
@@ -57,13 +57,13 @@ func (q *RelationQuery) ToURLQuery() url.Values {
 	v := make(url.Values, 7)
 
 	if q.Namespace != nil {
-		v.Add("namespace", *q.Namespace)
+		v.Add(NamespaceKey, *q.Namespace)
 	}
 	if q.Relation != nil {
-		v.Add("relation", *q.Relation)
+		v.Add(RelationKey, *q.Relation)
 	}
 	if q.Object != nil {
-		v.Add("object", *q.Object)
+		v.Add(ObjectKey, *q.Object)
 	}
 	if q.SubjectID != nil {
 		v.Add(SubjectIDKey, *q.SubjectID)
@@ -112,17 +112,17 @@ func (s *SubjectSet) FromURLQuery(values url.Values) *SubjectSet {
 		s = &SubjectSet{}
 	}
 
-	s.Namespace = values.Get("namespace")
-	s.Relation = values.Get("relation")
-	s.Object = values.Get("object")
+	s.Namespace = values.Get(NamespaceKey)
+	s.Relation = values.Get(RelationKey)
+	s.Object = values.Get(ObjectKey)
 
 	return s
 }
 
 func (s *SubjectSet) ToURLQuery() url.Values {
 	return url.Values{
-		"namespace": []string{s.Namespace},
-		"object":    []string{s.Object},
-		"relation":  []string{s.Relation},
+		NamespaceKey: []string{s.Namespace},
+		ObjectKey:    []string{s.Object},
+		RelationKey:  []string{s.Relation},
 	}
 }
diff --git a/ketoapi/public_api_definitions.go b/ketoapi/public_api_definitions.go
index 85636f8d2..1e96eac56 100644
--- a/ketoapi/public_api_definitions.go
+++ b/ketoapi/public_api_definitions.go
@@ -121,12 +121,26 @@ const (
 )
 
 const (
+	NamespaceKey           = "namespace"
+	ObjectKey              = "object"
+	RelationKey            = "relation"
 	SubjectIDKey           = "subject_id"
 	SubjectSetNamespaceKey = "subject_set.namespace"
 	SubjectSetObjectKey    = "subject_set.object"
 	SubjectSetRelationKey  = "subject_set.relation"
 )
 
+var RelationQueryKeys = []string{
+	NamespaceKey,
+	ObjectKey,
+	RelationKey,
+	SubjectIDKey,
+	SubjectSetNamespaceKey,
+	SubjectSetObjectKey,
+	SubjectSetRelationKey,
+	"subject", // We have a more specific error message for this key.
+}
+
 // Paginated Relationship List
 //
 // swagger:model relationships