Let's say the IRS wants to be able to confiscate bitcoins from tax evaders. So they go to the US courts to get this. A judge ends up ordering the bitcoin.org dev team to include a government backdoor so the IRS can take funds away from those who don't pay taxes.
The devs would be forced to comply right?
Open source software makes it so that every change is visible.
Currently the Bitcoin-Qt/bitcoind release is signed by the Bitcoin Foundation ... which means the release won't work for Windows 8 and Mac users (as an update) unless Bitconi Foundation signs it. This makes it difficult for some other dev team members who are not a party to this hypothetical IRS backdoor demand to be able to release updates to the client without this backdoor themselves. It would probably have to be a fork with a different name (and signed by some other organization).
But the developers don't have final say as to what changes are accepted for the Bitcoin protocol. It is the economic majority who decides:
-
http://en.bitcoin.it/wiki/Economic_majority