First of all I think it is important to make a distinction of the terms used constantly in this debate:
Approval for medical use- Many states already have this measure in place where marijuana can be used under the supervision of a physician who understands it's usefulness as a treatment for various ailments.
Decriminalized use- In a nutshell this means that it is not legal, but not a law enforcement priority. Implications would mean tolerance of small quantity possession and usage. This also means it cannot be sold legally but for example you can't be fired for not passing a drug test. In addition decriminalization still includes legal consequences such as fines, community service and required drug treatment as opposed to incarceration.
Legalization of use- Complete legalization of medical and non-medical cannabis. By this measure it means that people can set up shops to sell marijuana, the government can tax it, people can use it freely and commercial marijuana farms can be created.
That being cleared up in Puerto Rico, at the moment there are two main projects involving cannabis: Proyecto del Senado 517 (decriminalization of marijuana) and Proyecto de la Camara de Representantes 1362 (legalization of medical use marijuana). Therefore, speaking of the "legalization of marijuana" is useless because it is not even in consideration at the moment. This is a big sociological issue in PR, although not necessarily a political one since the governor Garcia Padilla himself has specified not to be the most important thing on agenda. The decriminalization or medical legalization of marijuana is never the less a big concern for many because of the possible economical and criminal implications tied to it. The truth is that there is a large financial investment in law enforcement officials to fight and prosecute individuals that use marijuana as a recreational drug.
One side of the debate establishes the medical benefits of the drug, the economical increase that could be obtained by reassigning funds from the drug war on marijuana to violent crimes instead, the decrease in crimes, gangs and black market sales and the diminished severity of its side affects in comparison to other legal substances such as alcohol or tabacco. The other side stands ground by saying it is an initiation drug, and users would start with marijuana and continue into other more harmful substances. Others in opposition state that the decriminalization would not solve the problem and in addition oppose with moral reasons.
This issue has been present in the US since the 1970's when Oregon became the first state to decriminalize cannabis in 1973, followed shortly by Alaska, California, Colorado, Mississippi, New York, Nebraska, North Carolina and Ohio. So why the big debate now in PR and the US included? Because now the US is talking about full legalization and PR finally caught up to talk about decriminalization. As with any substance legal or not, there have been good people and bad who use it, places where the decriminalization has worked and places where it failed miserably. To understand this issue it needs to be put into context in PR and look into how it has worked in our neighboring Latino countries who share a similar culture. There is a lot at stake by going down this rabbit hole because like it or not it is a domino effect: decriminalization today, legalization tomorrow (like in the US) and now it may be cannabis but in 30-40 years when this issue blows over; what will be the next one to be debated about?