A professor in casual conversation claimed that Spain started to become more liberal with the Constitution of 1812 and even though it wasn't continously upheld during the twenty five that it existed until 1837, that was one the main reasons why the reactionary conservative criollo elites of the New World decided to breakaway from Spain.
For starters, the new Constitution recognized as Spanish citizens people born in both hemispheres of the Empire and it abolished feudalism, granted universal voting rights to all men, equality before the law and civil rights for indigenous, free blacks and mixed race people, among other liberal clauses for its time such as free enterprise and press, a parliamentary system, etc. It was this and more that was directly challenging the diametrically opposed conversative mores and privileges of the landed aristocracy and other powerful interest groups in the Americas .
Was this really one the reasons why the reactionary colonial elites decided to separate from peninsular Spain? I have always been taught that it was the opposite: that the colonies were liberal and the motherland was conservative and this is why they chose to revolt.
Yes and no. You could say that the Americas were the traditional and Spain was modern. The new ideas about society in Spain collided with the "social archaism" of latam. The despotism of the monarchy was in the roots of the colony, which resulted in the re-emergency of neo-scholastic contractualist doctrines in the matter of articulation of the nation-state, opposed to the ideals of the Enlightenment, that were predominant in the mainland.
On the other hand, there was this thing in the Americas called "The Retroversion of the sovereignty to the people" which meant that God gave the people the sovereignty, and they consented in giving it to the king, Ferdinand VII, not to Spain. When Ferdinand was imprisioned by Napoleon and his brother José Bonaparte took the power in Spain, the retroversion broke, and the spanish colonies didn't claim independence, but instead formed Juntas de Gobierno that would replace the king until he was set free and returned to his place. When he came back, though, he wasn't the king that people wanted anymore, so they declared independance in 1816.
Sources (sorry, don't know the names in english): Elías Palti - Las ideas fuera de lugar José Carlos Chiaramonte - Autonomía e independencia en el Río de la Plata, 1808 - 1810 François-Xavier Guerra - Las revoluciones hispánicas: independencias americanas y liberalismo español
This is a little watered down but I think it is worth adding to the answers to your questions.
The Bourbon Reforms also played a huge part in setting the stage for independence.
Some of the major things:
When the Brits were able to capture “impenetrable Havana” and occupy the city during the 7 Years War, it provoked panic from Spain. In reaction, the Spanish set up militias of armed creoles and natives to better protect itself. This ended up backfiring big time, because it “put weapons in the hands of the little people” for the first time, and empowered them. Spanish gunpowder broke the Spanish Empire.
The Spanish, seeing that their once prosperous trade empire was lagging and it’s exports dwindling (compared to Golden Age levels), used guidance from the scientific acme of Europe at the time, France, in reorganizing and modernizing its trade. Mercantilism exploded as a result of these reforms and, though income skyrocketed, there was also unemployment for the first time EVER in New Spain. Communities were disrupted as these new practices were introduced.
Also, the Bourbon Reforms threated the “Two Republics” system and undermined the centuries-old protections that indigenous communities enjoyed. Spain had originally granted inalienable rights of the land to pre-existing villages in an effort to stabilize and organize its new subjects. The Bourbon Reforms saw new taxes and violations of autonomy that angered everyone. The clergy was under assault by the Spanish Government because they dominated local communities as well, and these respected clergymen (especially the Jesuits, who were forcibly exiled back to Italy) were seen as a threat to Spanish royal authority. The Jesuits were, indeed, considered “too liberal” by peninsulars because, although they started out as hardliner missionaries, they shifted over time. Since they were the ones talking, living, and learning the people of the New World, they eventually came to understand and advocate for them. This was troubling to Spain.
When you combine these effects from the Bourbon Reforms you can see the sources of animosity.