Legislators from pretty much every party save the PAN declared their opposition to the arraigo, the legal tactic which allows the government to hold suspected drug criminals for extended periods of time without charges. (I'm not exactly clear on what the limit is. When the judicial reform was passed last year, 80 days was said to be the limit, and I've never read anything contradicting that. However, I've never seen an arraigo of more than 40 days.)
The time period seems like the most important issue. I can be convinced that in certain cases (i.e., if someone is in the company of a bunch of known traffickers but isn't actually doing anything wrong), a suspect would need to be held without charges while an investigation is completed, but 40 days is excessive.