The ease of which

[capcap23]

The ease of which criminals obtain weapons does not change when firearms are made illegal. source

I can't comprehend the grammar of "the ease of which". It would make more sense to me if it was used with the preposition "with".

Is the use of the preposition "of" wrong? There are other instances with "of" so I'm in doubt. If it is not wrong, could you explain to me the grammar behind it?

 

[Rover_KE]

Only 'the ease with which' makes any sense. The use of 'of which' is wrong for me.

 

[jutfrank]

Right. You do something with ease.