It's not really a complete sentence. Apart from that, it would be more usual to use "corrupt", rather than corrupted", unless you were referring to a lawyer who had just been corrupted, and you wished to emphasise this.
It's understandable as a sentence if it's in response to something like "What do you think might happen in the court case?" or "What's the worst thing that could happen to the papers in those archives?"
Yes, as a conjunctive function word too, but I think an article is necessary as in "That the/a corrupted lawyer......"
I was using "that" to identify a specific corrupt lawyer who is already known to both parties.
That man over there just stole my cake!
That corrupt lawyer might pass over the papers
That car nearly ran me over.
That girl who reads the news has very strange hair.