The current redlining paradigm in use with most word processing solutions today needs improvement. It's consuming far too much of our time, and fails to express our intentions efficiently and accurately. There's a better way.
In US: must be an attorney licensed and in good standing in any state, territory or DC.
Outside US: must be a lawyer or equivalent (eg counselor, barrister, advocate, solicitor), duly educated and licensed/accredited and in good standing.
As a general rule, experienced and currently practicing lawyers, and those teaching law in the legal academy, are more likely to be admitted.