Social media sites are a burden to law enforcement in some ways, but they are also beneficial.
Social media sites can be a danger for individual law enforcement officers. Such people might get in trouble for things they post on social media. Social media sites could also cause more law enforcement problems as you have things like people coordinating crimes on these sites.
But social media sites are also helpful to law enforcement. Law enforcement officials can use things that are posted on these sites as ways to catch criminals. Suspects might post pictures or tweet updates that connect them to crimes. Because people post so much about themselves, it is possible that evidence of crimes will be posted where law enforcement can access it.