What are the Kentucky and Virginia Resolutions?

The Kentucky and Virginia Resolutions, respectively authored by Thomas Jefferson and James Madison, were responses to the Alien and Sedition Acts of 1798, which were enacted during the Quasi-War with the French Republic.  This was an undeclared naval war that resulted from economic considerations of the Jay Treaty with Britain that followed the American declaration of neutrality and further inflamed a French government already upset by America's refusal to pay its war debt under the auspices that the obligation was to the French monarchy, not the Republic.  Consequently, the French began seizing American ships that were trading with Britain and Congress issued "An Act further to protect the commerce of the United States" which authorized military action against France.

Domestically, American sentiment was divided between Democratic-Republicans, represented by Jefferson and Madison, and Federalists represented by Alexander Hamilton, a monarchist, and John Adams. Democratic-Republicans preferred to maintain constitutional integrity through strict constructionism, or the observance of the text as it was spoken, and they supported the French Republic because of its Democratic nature.  In contrast, Federalists preferred license provided through the concept of implied powers, an innovation of Alexander Hamilton that provided for the assumption of authority that was not explicitly granted by the Constitution, and they favored a close relationship with Britain.  Democratic-Republicans were typically small farmers while Federalists were usually wealthy.  Democratic-Republicans viewed Federalists as elitists who favored aristocracy and monarchy and Federalists considered Democratic-Republicans to be Jacobins who would use the principles of the French Revolution to overthrow the government.

Some of this sentiment was likely fueled by the Whiskey Act of 1791, an unpopular excise regarded as taxation without representation, that provoked violent resistance among western farmers.  A tax collector was tarred and feathered, shots were fired at Bowers Hill, a crowd gathered at Braddock's Field and spoke of declaring independence from the United States, and the tax went uncollected in Kentucky.  In 1794, the militia was called to put down the Whiskey Rebellion and this sparked draft evasion and riots before the army marched into western Pennsylvania and the insurgency dissolved.

In this heated political climate, just nine years after the ratification of the Constitution, the Alien and Sedition Acts were passed in 1798.  The Alien Acts, which were considered to be an infringement of the rights reserved to states by the Tenth Amendment and the due process provided by the Fifth Amendment, were largely directed towards French and Irish immigrants.  They extended residency requirements for citizenship and provided for the deportation of aliens who were deemed dangerous during times of peace and war.  The Sedition Act, which  prohibited public criticism of the Federal government, was spitefully used against Democratic-Republicans, flagrantly violating the guarantee of free speech provided by the First Amendment; it  read, in part:

And be it further enacted, That if any person shall write, print, utter or publish, or shall cause or procure to be written, printed, uttered or publishing, or shall knowingly and willingly assist or aid in writing, printing, uttering or publishing any false, scandalous and malicious writing or writings against the government of the United States, or either house of the Congress of the United States, or the President of the United States, with intent to defame the said government, or either house of the said Congress, or the said President, or to bring them, or either of them, into contempt or disrepute; or to excite against them, or either or any of them, the hatred of the good people of the United States, or to excite any unlawful combinations therein, for opposing or resisting any law of the United States, or any act of the President of the United States, done in pursuance of any such law, or of the powers in him vested by the constitution of the United States, or to resist, oppose, or defeat any such law or act, or to aid, encourage or abet any hostile designs of any foreign nation against the United States, their people or government, then such person, being thereof convicted before any court of the United States having jurisdiction thereof, shall be punished by a fine not exceeding two thousand dollars, and by imprisonment not exceeding two years.  (Emphasis added by the author.)

The Alien and Sedition Acts, justified via implied powers, resulted in the adoption of the Kentucky and Virginia Resolutions.  The Virginia Resolution of 1798 repudiated "forced constructions" of the Constitution, recognized the usurpation of authority, and the threat to state sovereignty imposed by the Federal government:

That the General Assembly doth also express its deep regret, that a spirit has in sundry instances, been manifested by the federal government, to enlarge its powers by forced constructions of the constitutional charter which defines them; and that implications have appeared of a design to expound certain general phrases (which having been copied from the very limited grant of power, in the former articles of confederation were the less liable to be misconstrued) so as to destroy the meaning and effect, of the particular enumeration which necessarily explains and limits the general phrases; and so as to consolidate the states by degrees, into one sovereignty, the obvious tendency and inevitable consequence of which would be, to transform the present republican system of the United States, into an absolute, or at best a mixed monarchy.

The Virginia Resolution also established that the states "... have the right, and are in duty bound, to interpose for arresting the progress of the evil, and for maintaining within their respective limits, the authorities, rights and liberties appertaining to them."  The Kentucky Resolutions of 1798 declared that Federal acts are void when the government assumes powers that are not delegated to it:

Resolved, That the several States composing, the United States of America, are not united on the principle of unlimited submission to their general government; but that, by a compact under the style and title of a Constitution for the United States, and of amendments thereto, they constituted a general government for special purposes — delegated to that government certain definite powers, reserving, each State to itself, the residuary mass of right to their own self-government; and that whensoever the general government assumes undelegated powers, its acts are unauthoritative, void, and of no force....

The Kentucky and Virginia Resolutions denounced the deliberate misconstruction of the "general welfare " and "common defence" clauses as unlimited grants of power beyond their context in the Articles of Confederation, (Report of 1799, Virginia House of Delegates) reaffirmed the narrow authority of the Federal government as provided by the Constitution and the intentions of its framers, and asserted the right of the states to defend public liberty from illegitimate Federal authority.  The Kentucky and Virginia Resolutions were the first formal attempts to lawfully combat Constitutional innovation and excess at the Federal level; they predate the formalization of judicial review, which is also an implied power, established by Marbury v. Madison in 1803.