Are libraries in control?

Libraries apparently don't have as much control as one would expect. But that could change.

It seems libraries were able to ban patrons for bad behavior (viewing pornography, shouting g obscenities, etc.), but could do nothing to actually enforce it. A new law in Pennsylvania will give libraries the authority to enforce written warnings and keep out those it has banned for the extent of the ban.

Naturally, it has opponents and supporters. Opponents say it gives libraries too much power, but the linked article mentions that most other entities--colleges, public schools, and more--have this same level of authority.