| United States | | | | | | | | | | | House of Representatives | Senate | | | | | | | | | | | | | | | | | | | | | | | President | | | | | | | | | | | | | |
| Austria | | | | | | | | | | President | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| Belgium | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Chamber of Representatives | | | | | | | | | | | | | | | | | | |
| Croatia | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Parliament | | | | | | | | | | | | | | | | | |
| Czech Republic | | | | | | | | | Senate | Chamber of Deputies | | | President | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Chamber of Deputies | | |
| Denmark | | | | | | Referendum | | | | | Parliament | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| The Netherlands | | | | | | | | | | | | | | | | | | | | | | | House of Representatives | | | | | | | | | | | | | | | | | | | | | | | | | |
| European Union | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Parliament | | | | | | | | | | | | | | | | | | |
| Finland | | | | | | | | | | | | | | | | Parliament | | | | | | | | | President | | | | | | | | | | | | | | | | | | | | | | | |
| France | | | | President | | National Assembly | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| Germany | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Bundestag | | |
| Greece | | | | | | | | | | | | | | | | | Parliament | Parliament | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| Iceland | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | President | | | | | | | | | | | | | | | Parliament | | | |
| Ireland | | | | | | | | | | | | | | | | | | | | | | | Referendum | | | | | | | | | | | | | | | | Parliament | | | | | | | | | |
| Italy | | | | | | Referendum | | | Chamber of Deputies&Senate | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| Latvia | | | | | | | | | | Parliament | | | | | | | President | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| Lithuania | | | | | | | | | | | | | | | | | | | | | | | | | | | | | President | | | | | Parliament | | | | | | | | | | | | | | |
| Montenegro | | | | | | | | | | | | | | | President | | | Assembly | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| Norway | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Parliament | | | |
| Poland | | | | | | | | | | | | | | | | | | | | | | Parliament | | | | | | | | | | | | | | | | | | | | President | | | | | | |
| Portugal | Assembly | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| Romania | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | President | | | | Chamber of Deputies & Senate | | | | | | | | | |
| Serbia | Referendum | | | National Assembly & President | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| Slovakia | | | | | | | | | | | | | Referendum | | | | | | | | National Council | | | | | | | President | | | | | | | | | | | | | | | | | | | | |
| Slovenia | | | | National Assembly | | | | | | President | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| Spain | | | | | | | | | | | | | | | | | | | Congress of Deputies&Senate | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| Sweden | | | | | | | | | Parliament | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| Switzerland | | Popular vote | | | Popular vote | | | | Popular vote | | | | | | | | | Popular vote | | | | Federal Assembly | Popular vote | | | | Popular vote | | | Popular vote | | | Popular vote | | Popular vote | | | Popular vote | | | Popular vote | | | | Popular vote | | Popular vote | |
