Is regressive tax unconstitutional?

In contrast with progressive tax which is proportional, a regressive tax is paid uniformly by taxpayers regardless of their ability to pay, and without due regard to their income. Hence, the poor pays the same tax as the rich. Indirect taxes such as Excise tax and Value Added Tax are examples of this. These taxes are passed on ultimately to the consumer of goods and services who bears the brunt of resultant price increase in prime commodities. What makes it unconstitutional is the fact the 1997 Philippine Constitution (Article VI, Section 28) calls for the evolution of the Philippine tax system into a progressive one, meaning a tax system that considers the taxpayer's ability to pay in relation to his income. Two decades had passed, but instead of evolving towards a progressive tax system, the Philippines has devolved deeper into a regressive tax system by increasing the excise tax on gasoline, grease, and lubricants. It now imposes an excise tax on diesel, and LPG's. Similarly, certain VAT exemptions were eliminated, subjecting more economic activity to VAT. While it is true that income taxes were lowered to hopefully mitigate the adverse effect of regressive taxes, it is also true that the cost of living is constantly and steadily on the rise, leaving the income earners decades behind. The projected benefit of income tax reduction may only be a means to partially cope with the soared and soaring prices, and frankly, it is way long overdue. Meanwhile, the cruel blow to the purchasing power of the ordinary Filipinos may have yet to come.