Sweden’s Keyhole Solution

As I explain in Open Borders, a responsible advocate of government intervention always asks, Is there any cheaper and more humane approach?  Government should do something is perfectly consistent with Scrupulously avoid collateral damage.  Following Tim Harford, I call such responsible approaches keyhole solutions.  This recent AIER piece from James Cooper (via Dan Klein) provides a fine example:

I am an American living in Stockholm. I have been living here for 17 years and am fluent in...