Since under international law no one may be compelled to join a political association[i], “Unless the electoral system is restricted to parties or party lists, individuals should not be precluded from being nominated as independent or unaffiliated candidates.”[ii]

However, in practical terms the possibility of independent candidates’ participation in electoral processes is quite limited in most parliamentary systems. These systems consider that in elections, at least at the national level, only parties can truly compete. This is often especially the case where only parties have the right to receive public funding.

 
Independent candidates and groups of non-affiliated candidates often have so limited practical and legal possibilities to participate in elections that their role in modern democracies is marginal. The following restriction can be identified:

• The nomination of independent candidates is usually subject to some specific requirements regarding support by a certain number of signatures;
• Independent candidates are often obliged to pay a deposit;
• They usually have limited access to free broadcast  time in public media, and
• They rarely have the right to receive in advance public contributions to their election campaigns.

Article 220 (4) of the Spanish electoral law is illustrative of the requirement of a certain number of signatures. In practice, the signature requirement is eliminated for political parties given that the 15,000 signatures required for the nomination of candidates can be replaced with the signatures of 50 elected officials at any level, even municipal. In this case, groups of non-affiliated candidates that usually do not have the possibility to be supported by 50 elected officials, must present 15,000 signatures. In addition, the possibilities for independent candidates to run big electoral campaigns are generally very limited unless they have their own significant financial resources (think of the case of Ross Perot, who largely self-financed two successive U.S. Presidential election campaigns. Indeed, the second time he obtained a reduced number of votes, partly because he was also excluded from access to the Presidential media debates).

Elections of a limited scope, such as local elections, where independent candidates or groups of non-affiliated candidates can compete with limited means constitute an exception to this rule.

On the contrary, in presidential systems, usually more emphasis is placed on the personality of the candidate. As a result, the role of political parties in the nomination of candidates is less important. This is a consequence of the different distribution of powers between a directly elected president and members of the Chambers who are affiliated with a party. In these cases, the nomination by a political party is not always sufficient but there is often a requirement of a certain number of signatures from citizens.

Another aspect that should be considered when establishing the possibility for nominations of independent candidates and the accompanying registration requirements is the principle of equality, and that the registration requirements must not discourage participation. At the same time, regulation should generally provide mechanisms that discourage the scattering of votes and the attendant deterioration of the party system.