Question

A new law was enacted by the Philippine legislature that significantly increased the tax rates for individuals earning above a certain income threshold. The law took effect immediately upon its publication in the Official Gazette. Several individuals who earned income above the threshold during the previous fiscal year were concerned about the retroactive application of the new law and its impact on their tax liabilities.

Discuss the retroactivity of laws and its application to the situation of the individuals affected by the new tax law. Consider the principles embodied in Article 4 of the Civil Code and the concept of vested rights. Provide an analysis of whether the retroactive application of the law would be reasonable and justifiable in this particular scenario.

1. Identify the relevant provisions of Article 4 of the Civil Code that pertain to the retroactivity of laws.
2. Explain the concept of vested rights and its significance in relation to retroactive laws.
3. Discuss the factors that must be considered to determine the reasonableness and justifiability of retroactive application of laws.
4. Analyze the situation of the individuals affected by the new tax law and assess whether the retroactive application of the law would be fair and equitable in this case.