Ignoring the technical implementation of a website for a second, assume a website that is similar to twitter but with pictures.

A user say something and puts a picture of whatever they said. As the nature of the internet, the images will most likely not be his/hers image.

There are 2 options that I see for dealing with this: 1. The user will post a URL of the picture and the website will pull the picture from that URL everytime someone enters that page 2. The website will save the image in its own database of images and display the image to the visitors 'locally'

The problem with option #1, while it saved storage, I see an issue with 'stealing' other websites bandwidth and if my website has many many visitors it could cost the image-hosting websites a lot and possible even crash it if the server can't handle the load.

The problem with opion #2, while it saves the load to other websites, it practically takes pictures that could have copyright on them.

Which option is better to implement in terms of legal issues and ethics?

When do I need to contact another website to request permission to use the images from that site? Does anyone really care about that anymore.

Where can I read about this?