Question

Question:

Mr. Santos purchased a property from Mr. Reyes in 2015. At that time, there was an existing law that allowed the sale and transfer of land regardless of their classification. However, in 2018, a new law was enacted declaring all agricultural lands as non-transferable. Mr. Santos now wants to know if the new law can be applied retroactively to invalidate his ownership of the property.

In light of the given scenario, discuss the effect and application of Article 4 of the Civil Code on the retroactivity of laws. Determine whether Mr. Santos' ownership of the property can be affected by the enactment of the new law. Cite relevant laws and principles to support your analysis.

Furthermore, evaluate the principle of vested rights and its application in this situation. Determine whether Mr. Santos' acquisition of the property can be considered a vested right that should be protected despite the enactment of the new law.