Brutus was also a pseudonym
used by the "anti-federalists" early in the history of the United States
. The "anti-federalists" as their name
implies wanted a less centralized government
states would have more power.
Rather than publish opinions under their own name, the framers of the constitution sent essays anonymously to local newspapers to convince the public that their way was better. Alexander Hamilton and James Madison, most famously, published under the pen name "Publius" what became the "Federalist" (commonly called "the Federalist Papers") later with John Jay.