So, there's a poster that I had made for a fundamentally the same question and I might want to share it with you here, as well :)
Just two or three words of explanation:
- I used the magnifying glass in order to attempt and express the transparency
- it's something that reveals what's covered up. Just like we should reveal the shrouded acts of corruption.
- The wall is just a placeholder you may say. That's a background as good as any. It looks like a graffiti thanks to the wall so I kind of consider it as a plus. It gives that modern feeling as well as shows that normal individuals care about that. That's because graffiti is a sort of expression used mainly by individuals who might not be heard otherwise.
- The call for action is just a tweak. The picture seemed really emplty without it.
I trust you'll like the poster! :)