"by counsel" is correct and usable in written English.
It is usually used to refer to advice or guidance given to someone. For example, "He made his decision by counsel from his legal advisors".
Mr. Panetti was represented by counsel in both trials.
You have the right to appear and testify, call witnesses and be represented by counsel".
The most important right has been the right to be represented by counsel.
The submissions released by counsel assisting the royal commission run to more than 800 pages.
Marines called as parties have the right to be represented by counsel in the hearings.
At certain points, they are not allowed to be represented by counsel.
Once you start talking, you are basically waiving your right to be represented by counsel".
Mr. Milosevic, I see that you're not represented by counsel today.
They said the judges could name a stand-by counsel who could step in at short notice.
The role of the Amici Curiae in the Milošević case was innovative in that they functioned, in practical terms, as stand-by counsel to a pro se accused.
The Assigned Counsel were thus effectively returned, by the Appeals Chamber, to the previous role they had occupied while they were Amici Curiae, which was, in essence, stand-by counsel.
