Any legal eagles here that can explain to me, more fully, the Monroe Doctrine?

1823 they were forcibly applied to the suppression of the
parliamentary system of the Spanish monarchy, and then threat-
ened the colonies. It is quite credible that at that period only
the great waste of the Atlantic waters saved the American
republics from a conflict for their national life. Even this wide
desert boundary did not save Mexico so late t~s 1864-~5 from the
vital sfruggle between European and American pditical systems.
It may be admitted that the principles in question, as declared
by Mr. Monroe, were limited to these two points: First. That no
foreign power should establish thereafter, as of their own right, a
colony within the territories of any of the de facto independent
states of America, meaning thereby to include all parts of both
continents not at that time held as colonial possessions. ~S~econd.
That no European power should attempt by force to introduce
monarchical institutions into any American territory, or otherwise
interfere to oppress the American states, or control their inde-
pendent development.
http://memory.loc.gov/cgi-bin/query/r?a ... 78-0133-44))::

This is part of an article.....I know it was against European colonization, but it has been used in other ways,....does it now, apply to the situation with Mexico?