[kevincox]

I don't follow this topic closely but it is definitely in a legal grey area and under frequent debate (and lawsuits).

To highly summarize...

A frequent allegation is that this is unauthorized access of computer systems. The scrapers argue that this is public data so they are just accessing it. Their access isn't meaningfully different from regular users which are allowed. From their point of view if the service doesn't want to share the data they shouldn't make it available.

Another common accusation is breaching the ToS. Generally the defense is that they didn't agree to any contract.

A last effort is some sort of copyright. Generally the scrapers will argue that that the data can't be copyrighted, isn't owned by the service or that some sort of license was given (back to the public data argument).

Of course every case is different and has different points but these are the common ones that I have seen.

[saurik]

Potentially useful reference regarding the status of one of the most important such lawsuits:

https://news.bloomberglaw.com/us-law-week/supreme-court-scra...

[tomatowurst]

yeah post linkedin, it gave the green light to scrape any publicly available information. Craiglist bullied scrapers via lawsuit (EFF covered it) but post linkedin, there has been zero grounds for Craigslist to use the DDOS argument (since the website is built to handle far more traffic than scrapers can).