What are the similarities and differences? OLD exemplifies but doesn't contrast them:
5 [transitive, intransitive] to argue in support of somebody/something
[5.1.] plead something
[Example:] She appeared on television to plead the cause of political prisoners everywhere.
[5.2.] plead for somebody/something
[Example:] The United Nations has pleaded for a halt to the bombing.
What would happen if 5.1 used plead for, and 5.2 plead?
Also, why does plead for a stay prevail over plead a stay?
My interpretation is "plead something" has legal overtones and implies you're arguing or claiming as you might in a trial. "Plead the 5th" is sometimes used jokingly in conversation in the US to mean "I'm not going to say anything more" and is a reference to exercising your constitutional right under the 5th amendment to not incriminate yourself. It is related somewhat to legal pleading but it isn't always about a legal situation.
After my scholarship was unfairly revoked, I went to the provost to plead my case for it to be reinstated.
To "plead for" has less of a legal connotation and is more synonymous with "to beg or to implore".
Rodney King plead for an end to the rioting in Los Angeles when he said
People, I just want to say, can we all get along?
...why does plead for a stay prevail over plead a stay?
Plead = to present the facts/arguments
Plead for = to ask|petition the court to take some action
When asking the court to issue a stay, counsel pleads for a stay.
