diff --git a/src/onegov/core/filters.py b/src/onegov/core/filters.py
index 08d4fc5677..5fcf247ca4 100644
--- a/src/onegov/core/filters.py
+++ b/src/onegov/core/filters.py
@@ -4,8 +4,8 @@
 import os
 import rcssmin  # type:ignore[import-untyped]
 
-from webassets.filter import Filter, register_filter  # type:ignore
-from webassets.filter.datauri import (  # type:ignore[import-untyped]
+from webassets.filter import Filter, register_filter
+from webassets.filter.datauri import (
     CSSDataUri, CSSUrlRewriter)
 from dukpy.webassets import BabelJSX  # type:ignore[import-untyped]
 from dukpy import jsx_compile  # type:ignore[import-untyped]
@@ -49,10 +49,10 @@ def setup(self) -> None:
         self.transformer = jsx_compile
 
 
-register_filter(JsxFilter)
+register_filter(JsxFilter)  # type:ignore[no-untyped-call]
 
 
-class DataUriFilter(CSSDataUri):  # type:ignore[misc]
+class DataUriFilter(CSSDataUri):
     """ Overrides the default datauri filter to work around this issue:
 
     https://github.com/miracle2k/webassets/issues/387
@@ -67,26 +67,28 @@ def input(self, _in: IO[str], out: IO[str], **kw: Any) -> None:
         self.source_path = self.keywords['source_path']
         self.output_path = self.keywords['output_path']
 
-        return super(CSSUrlRewriter, self).input(_in, out, **kw)
+        return super(CSSUrlRewriter, self).input(_in, out, **kw)  # type:ignore[no-untyped-call]
 
     @property
     def source_url(self) -> str:
+        assert self.ctx is not None
         return self.ctx.resolver.resolve_source_to_url(
             self.ctx, self.keywords['source_path'], self.keywords['source'])
 
     @property
     def output_url(self) -> str:
+        assert self.ctx is not None
         return self.ctx.resolver.resolve_output_to_url(
             self.ctx, self.keywords['output'])
 
 
-register_filter(DataUriFilter)
+register_filter(DataUriFilter)  # type:ignore[no-untyped-call]
 
 
-class RCSSMinFilter(Filter):  # type:ignore[misc]
+class RCSSMinFilter(Filter):
     """ Adds the rcssmin filter (not yet included in webassets) """
 
-    name = 'custom-rcssmin'
+    name = 'custom-rcssmin'  # type:ignore[assignment]
 
     def setup(self) -> None:
         self.rcssmin = rcssmin
@@ -95,4 +97,4 @@ def output(self, _in: IO[str], out: IO[str], **kw: Any) -> None:
         out.write(self.rcssmin.cssmin(_in.read()))
 
 
-register_filter(RCSSMinFilter)
+register_filter(RCSSMinFilter)  # type:ignore[no-untyped-call]
diff --git a/src/onegov/swissvotes/collections/votes.py b/src/onegov/swissvotes/collections/votes.py
index 31b1d60050..11104b2244 100644
--- a/src/onegov/swissvotes/collections/votes.py
+++ b/src/onegov/swissvotes/collections/votes.py
@@ -71,6 +71,10 @@ def __init__(
         sort_by: str | None = None,
         sort_order: str | None = None
     ) -> None:
+        # ignore empty policy areas swi-63
+        if policy_area and '' in policy_area:
+            policy_area = [i for i in policy_area if i]
+
         super().__init__(page)
         self.app = app
         self.session = app.session()
diff --git a/src/onegov/swissvotes/converters.py b/src/onegov/swissvotes/converters.py
new file mode 100644
index 0000000000..32f9bc2c3b
--- /dev/null
+++ b/src/onegov/swissvotes/converters.py
@@ -0,0 +1,50 @@
+from __future__ import annotations
+import re
+from typing import TYPE_CHECKING
+
+import morepath
+
+
+if TYPE_CHECKING:
+    PolicyAreaConverterBase = morepath.Converter[str]
+else:
+    PolicyAreaConverterBase = morepath.Converter
+
+
+class PolicyAreaListConverter(PolicyAreaConverterBase):
+
+    def verify_format(self, s: str) -> bool:
+        # verify is a number or in '1.13.136' format,
+        # no alphanumeric character allowed
+        return bool(re.fullmatch(r'\d+(\.\d+)*', s))
+
+    def verify_components(self, s: str) -> bool:
+        # verify that componenet starts with previous component if
+        # split over `.` valid '1.12.123' but invalid '1.22.123'
+        components = s.split('.')
+        if len(components) == 1:
+            return True
+
+        for component in components[1:]:
+            if not component.startswith(
+                    components[components.index(component) - 1]):
+                return False
+
+        return True
+
+    def validate(self, s: str) -> bool:
+        """ Basically drops invalid policy areas. """
+        if not s:
+            return False
+
+        return self.verify_format(s) and self.verify_components(s)
+
+    def decode(self, s: str) -> list[str]:  # type: ignore[override]
+        if not s:
+            return []
+        return [item for item in s if self.validate(item)]
+
+    def encode(self, l: list[str]) -> list[str]:  # type: ignore[override]
+        if not l:
+            return []
+        return [item for item in l if item]
diff --git a/src/onegov/swissvotes/path.py b/src/onegov/swissvotes/path.py
index 3fc02b96b6..e3c3f26682 100644
--- a/src/onegov/swissvotes/path.py
+++ b/src/onegov/swissvotes/path.py
@@ -7,6 +7,7 @@
 from onegov.swissvotes.app import SwissvotesApp
 from onegov.swissvotes.collections import SwissVoteCollection
 from onegov.swissvotes.collections import TranslatablePageCollection
+from onegov.swissvotes.converters import PolicyAreaListConverter
 from onegov.swissvotes.models import Principal
 from onegov.swissvotes.models import SwissVote
 from onegov.swissvotes.models import SwissVoteFile
@@ -54,7 +55,7 @@ def get_locale(app: SwissvotesApp, locale: str) -> SiteLocale | None:
         'to_date': extended_date_converter,
         'legal_form': [int],
         'result': [int],
-        'policy_area': [str],
+        'policy_area': [PolicyAreaListConverter(str)],
         'term': str,
         'full_text': bool,
         'position_federal_council': [int],
diff --git a/stubs/more/webassets/directives.pyi b/stubs/more/webassets/directives.pyi
index af3e657ee2..16cebd153b 100644
--- a/stubs/more/webassets/directives.pyi
+++ b/stubs/more/webassets/directives.pyi
@@ -3,7 +3,7 @@ from collections.abc import Callable, Collection, Iterator, Mapping, Sequence
 from typing_extensions import Self, TypeAlias
 
 from dectate import Action
-from webassets import Bundle, Environment  # type: ignore[import-untyped]
+from webassets import Bundle, Environment
 
 _Filter: TypeAlias = str | Collection[str] | None
 
diff --git a/stubs/more/webassets/tweens.pyi b/stubs/more/webassets/tweens.pyi
index 3e4c65d94a..b410673edd 100644
--- a/stubs/more/webassets/tweens.pyi
+++ b/stubs/more/webassets/tweens.pyi
@@ -4,7 +4,7 @@ from urllib.parse import unquote as unquote
 
 from more.webassets.core import IncludeRequest
 from morepath.request import Request, Response
-from webassets import Environment  # type: ignore[import-untyped]
+from webassets import Environment
 
 CONTENT_TYPES: set[str]
 METHODS: set[str]
diff --git a/tests/onegov/swissvotes/test_collections.py b/tests/onegov/swissvotes/test_collections.py
index 3bde208f92..aabb44502f 100644
--- a/tests/onegov/swissvotes/test_collections.py
+++ b/tests/onegov/swissvotes/test_collections.py
@@ -100,7 +100,7 @@ def test_votes_default(swissvotes_app):
         to_date=4,
         legal_form=5,
         result=6,
-        policy_area=7,
+        policy_area=['7'],
         term=8,
         full_text=9,
         position_federal_council=10,
@@ -114,7 +114,7 @@ def test_votes_default(swissvotes_app):
     assert votes.to_date == 4
     assert votes.legal_form == 5
     assert votes.result == 6
-    assert votes.policy_area == 7
+    assert votes.policy_area == ['7']
     assert votes.term == 8
     assert votes.full_text == 9
     assert votes.position_federal_council == 10
diff --git a/tests/onegov/swissvotes/test_converters.py b/tests/onegov/swissvotes/test_converters.py
new file mode 100644
index 0000000000..c559fe8022
--- /dev/null
+++ b/tests/onegov/swissvotes/test_converters.py
@@ -0,0 +1,37 @@
+from onegov.swissvotes.converters import PolicyAreaListConverter
+
+
+def test_policy_area_converter():
+    converter = PolicyAreaListConverter(str)
+
+    assert converter.decode(['']) == []
+    assert converter.decode([None]) == []
+    assert converter.decode([]) == []
+    assert converter.decode(['1']) == ['1']
+    assert converter.decode(['1', '4']) == ['1', '4']
+    assert converter.decode(['1', '4', '8', '10']) == ['1', '4', '8', '10']
+    assert converter.decode(['1', '', '8', '22']) == ['1', '8', '22']
+    assert converter.decode(['1', '', '', '22']) == ['1', '22']
+
+    assert converter.encode(None) == []
+    assert converter.encode('') == []
+    assert converter.encode([]) == []
+    assert converter.encode(['1']) == ['1']
+    assert converter.encode(['21']) == ['21']
+    assert converter.encode(['1', '4']) == ['1', '4']
+    assert converter.encode(['1', '4', '8', '10']) == ['1', '4', '8', '10']
+
+    assert converter.decode(['1.12']) == ['1.12']
+    assert converter.decode(['1.12.121']) == ['1.12.121']
+    assert converter.decode(['4.42.421']) == ['4.42.421']
+    assert converter.decode(['10.102']) == ['10.102']
+    assert converter.decode(['10.103.1035']) == ['10.103.1035']
+    assert converter.decode(['12.125.1251']) == ['12.125.1251']
+    assert converter.decode(['1.12.123.1231']) == ['1.12.123.1231']
+
+    # invalid policy area(s)
+    assert converter.decode(['z']) == []
+    assert converter.decode(['1,12,121']) == []
+    assert converter.decode(['1.32.121']) == []
+    assert converter.decode(['4.92.421']) == []
+    assert converter.decode(['a.a2.a21']) == []
diff --git a/tests/onegov/swissvotes/test_views_votes.py b/tests/onegov/swissvotes/test_views_votes.py
index f4460ee495..c977893526 100644
--- a/tests/onegov/swissvotes/test_views_votes.py
+++ b/tests/onegov/swissvotes/test_views_votes.py
@@ -281,3 +281,16 @@ def test_view_update_external_resources(mfg, sa, bs, swissvotes_app):
 
     assert '15 hinzugefügt, 17 geändert, 19 gelöscht' in manage
     assert 'Quellen konnten nicht aktualisiert werden: 4, 8, 9' in manage
+
+
+def test_view_votes_empty_policy_area(swissvotes_app):
+    """ Ensure that the votes view does not crash when the policy area is empty
+    """
+    client = Client(swissvotes_app)
+    client.get('/locale/de_CH').follow()
+
+    page = client.get('/votes')
+    assert page.status_code == 200
+
+    page = client.get('/votes?term=&policy_area=9&policy_area=')
+    assert page.status_code == 200