The universal declaration of human rights is a good starter on the traits of a liberal democracy.
Here is info about how freedom house measures countries
Is the US free? Yes. We currently score an 83/100. However, our score has been declining. We were at 94/100 in the year 2010. Then the GOP won congress, did a bunch of gerrymandering, Trump and MAGA came about, and we’ve dropped from 94 to 83. Our score will likely be even lower when the 2025 report comes out due to Trump’s weaponization of law enforcement and ignoring judges.
I think the cutoff between ‘free’ and ‘partly free’ may be around 68/100.
The US earned 83 out of 100 possible points this year in Freedom House’s annual rankings of freedoms around the world, an 11-point drop from its ranking of 94 a decade ago. The US’s new ranking places it on par with countries like Panama, Romania and Croatia and behind countries such as Argentina and Mongolia. It lagged far behind countries like the United Kingdom (93), Chile (93), Costa Rica (91) and Slovakia (90).
Out of 193 countries and territories, the US is currently #56. Finland is #1 with 100/100