The messenger

Graphic design is a meta field, in the sense that it only exists in relation to something else. Someone else's content. Then we as graphic designers add a layer of design and make it more communicative.
I am wondering whether the fact, that it is not often us who create the content, affect the way we think about our work? Does it make us less responsible?
What if a client asks you to communicate something which you know is a lie? Do you care as long as there are fun design-experiments to be made?
"Don't shoot the messenger!" is what I come to think of.

Journalism which is also a meta field have very clear guidelines for their practise. They have a "Code of Ethics"which protects the main public -but also the journalists, in the sense that they have something to relate to, and hold on to, when they are confronted with difficult issues. http://www.spj.org/ethicscode.asp

I am wondering whether our profession would gain from "some kind of code of ethics"?
I know that a group of designers tried to do something like that, with the First things First" manifesto (1964 and 2000) http://www.xs4all.nl/~maxb/ftf2000.htm
which stirred a huge debate. I am still not sure whether it helped, or whether it was just the people who already agreed who cheered...