How has RA 10951 improved the Penal Code?

On August 29, 2017, President Rodrigo Roa Duterte signed into law Republic Act No. 10951 that sought, among others, to help indigent prisoners and individuals accused of committing petty crimes. It also increased the fines for treason and the publication of false news; and likewise increased the baseline amounts and values of property and damage to make them commensurate to the penalties meted on the offenses committed in relation to them.

Basic wisdom underlies the adjustments made by Republic Act No. 10951. Imperative to maintaining an effective and progressive penal system is the consideration of exigencies borne by the passage of time. This includes the basic economic fact that property values are not constant. To insist on basing penalties on values identified in the 1930s is not only anachronistic and archaic; it is unjust and legally absurd to a moral fault.In his dissenting opinion in Corpuz v. People, Justice Roberto Abad illustrated in the context of qualified theft the cruelty foisted by insistence on the values set by the Revised Penal Code when it was originally adopted:
The harshness of this antiquated 1930 scheme for punishing criminal offenders is doubly magnified in qualified theft where the offender is a domestic helper or a trusted employee. Qualified theft is a grievous offense since its penalty is automatically raised two degrees higher than that usually imposed on simple theft. Thus, unadjusted for inflation, the domestic helper who steals from his employer would be meted out a maximum of: 
[1] 6 years in prison for a toothbrush worth P5;  [2] 12 years in prison for a lipstick worth P39; 
[3] 14 years and 8 months in prison for a pair of female slippers worth P150; 
[4] 20 years in prison for a wristwatch worth P19,000; or 
[5] 30 years in prison for a branded lady's handbag worth P125,000. 
Unless checked, courts will impose 12 years maximum on the housemaid who steals a P39 lipstick from her employer. They will also impose on her 30 years maximum for stealing a pricy lady's handbag. This of course is grossly obscene and unjust, even if the handbag is worth P125,000.00 since 30 years in prison is already the penalty for treason, for raping and killing an 8-year-old girl, for kidnapping a grade school student, for robbing a house and killing the entire family, and for a P50-million plunder.

It is not only the incremental penalty that violates the accused's right against cruel, unusual, and degrading punishment. The axe casts its shadow across the board touching all property-related crimes. This injustice and inhumanity will go on as it has gone on for decades unless the Court acts to rein it in.[34] (Citations omitted.)
Given its possibly fairer and more just consequences, Republic Act No. 10951 is a welcome development in our legal system.

Republic Act No. 10951 likewise specifically stipulates that its provisions shall have retroactive effect. Section 100 adds that this retroactivity applies not only to persons accused of crimes but have yet to be meted their final sentence, but also to those already "serving sentence by final judgment."

This retroactivity is in keeping with the principle already contained in Article 22 of the Revised Penal Code that "[p]enal laws shall have a retroactive effect in so far as they favor the person guilty of a felony."

Given these circumstances, in People v. Mejares (G.R. No. 225735. January 10, 2018), the Supreme Court had to adjust the penalty to be imposed on accused-appellant.