Are there any countries that require political parties to be democratically organised (and accept members)?

Question

In many countries, members of parliament are elected on the title of political parties. For example, in The Netherlands, 81 parties have registered for the Dutch General Election, 2017. In most of those parties, the political programme and electoral lists are — at least in theory — democratically decided by the members. One of those parties (Party for Freedom, currently polling as the largest party at 21% of the vote), only has a single member (Geert Wilders). The party itself is effectively a dictatorship (but literally speaking, also a perfect democracy).

I have read a proposal (not supported by Mr. Wilders) to require parties that wish to participate in the elections to be democratically organised and member-based, arguing that it would make democracy less vulnerable (the wannabe-dictator could then be ousted by his own party members even if he has a majority in parliament). Regardless of whether or not such a requirement would actually help, my question is:

Are there any parliamentary systems where such a requirement for political parties exists, to accept members and be democratically organised?

Answer 1

Yes, in neighboring Germany for example. The German Grundgesetz (constitution) Article 21, Section 1, says (original German | official English translation):

(1) Political parties shall participate in the formation of the political will of the people. They may be freely established. Their internal organisation must conform to democratic principles. [...]

The Political Parties Act (PartG) implements this article with some more specific restrictions on how parties need to be organized internally.

A one-person-party would not be legal according to this law. Section 2 (10) says that parties must "offer a sufficient guarantee of their sincerity [...] especially as regards the size and strength of their organization, their membership numbers and their visibility in public". It doesn't give a specific minimum size, but I doubt anyone would disagree that "one" is insufficient. Further, section 10 (1) says "No general refusal to admit new members, even if of limited duration, shall be permissible.". That means parties must be open to accepting new members. Even though they don't need to accept everyone. The same section also reads "the party shall freely decide on the admission of members. No reasons need to be given for rejecting an application for membership". So if a party claims to be open to new members but rejects everyone for undisclosed reasons, it's up to the prosecution to prove that they refuse everyone and are not just very picky.

Answer 2

I think requirements of internal democracy are quite general.

Spanish constitution as another example:

Article 6. Los partidos políticos (...) Su estructura interna y funcionamiento deberán ser democráticos.

My translation:

Their [of political parties] internal structure and function must be democratic.

The law on political parties is more specific (article 3 j), when stating what should be in party bylaws:

j) El procedimiento para la elección de los órganos directivos, bien directamente o por representación, que en todo caso deberá garantizar la participación de todos los afiliados mediante sufragio libre y secreto, y los procedimientos de control democrático de los dirigentes electos.

My translation:

The process to elect directive positions, directly or by representations, that in any case must allow participation of all members through free and secret suffrage, and the democratic control of elect directive members.

Articles 6, 7 and 8 expand on that.

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Update:

The sources pointed by CptEric ask for a minimum of 3 members as any other association. However, I'm not sure about if a party could be registered with less members, mainly because the law of political parties doesn't reference the laws about associations, which aren't uniform in the whole country. Probably, if a party were rejected registering because of lack of enough members, the issue could end in court.