"Under no circumstances can our encryption be bypassed, meaning emails, attachments, calendars, files, etc. cannot be compromised by legal orders."
I hate this type of grandstanding. If the swiss authorities make a legal order demanding that protonmail include a rogue JS file when a specific IP address requests their inbox, they will have to do it. It reminds me of XKCD #538, All this advanced tech to make it so everyone trusts their email is encrypted no-matter-what and it all falls apart with one subpoena.
Oh, and apparently (According to this blog post) they 'wouldnt be able to fight or appeal' that type of order either. This is basically how PRISM was implemented back in the day, The NSA mandated various providers comply with code changes.