There’s no question San Marino is a full liberal democracy – its republican and democratic roots run centuries deep. However, as a microstate, there is an asterisk to this statement.
San Marino Watch posted a few years back about the work of Dutch political scientist Wouter Veenendaal, who studies democracy in small nations. There’s an longstanding truism in political studies that small countries – microstates and island nations – tend to be more democratic due to the proximity between the voters and the elected. Veenendaal uses San Marino as a case study to see just how this proximity turns out in real life.
Veenendaal found that the smallness of San Marino does lead to close interactions between the public and the elected, as well as robust democracy and high political engagement. He also found that this proximity means that hard ideology of any flavour has a hard time establishing itself (notably how San Marino had an elected communist government that was operating within the democratic system instead of fomenting revolution in the years before the Rovereta Affair). However, the unsurprising downside is that in such a small country, the political elite can become “cliquey” and that clientalism and conflicts of interest can become a major issue. You can read more on Veenendaal’s findings with added Sammarinese commentary on San Marino Watch.
Like most European microstates, San Marino has a financial system that provides a tax shelter for foreign funds, and as a fully sovereign nation, it can use the sovereignty itself to its own benefit (see: Nauru). This can lead to some very microstate-ish issues, such as issuing diplomatic positions to wealthy foreigners (including, bafflingly, Sting) and connections to shady businesspeople and companies. The most notable scandal out of San Marino recently was the Conto Mazzini case, where in 2017 many members of the political elite, including several former Captains Regent, were convicted on charges of money laundering and bribery.
That being said, San Marino ranks a healthy 93/100 on Freedom House’s Global Freedom Score, and the fact that the Conto Mazzini case was a huge scandal that led to convictions of the powerful shows a real commitment to transparency and rule of law.