Google: 'Government surveillance is on the rise'
In 90% of all requests by the government to access a personal email account Google agreed.
This is why it's a good idea to encrypt your emails. I can't do it universally, due to not everyone whom I email having encryption software (or in some cases not knowing how to use the encryption software that others installed for them), but I can do it for those with whom I most want to keep a secure email link.
The government can almost certainly "brute-force" its way past an encryption with ease, but it does prevent them, or anyone else, be they criminals, or even even the email provider, from casually reading your emails, absent an unknown security exploit.
My personal suggestion is GPG (link is for the windows version).