Short answer: Florida election law Section 101.514(5) promulgates the following standard for canvassing votes rejected by the counting machines: "No vote shall be declared invalid or void if there is a clear indication of the intent of the voter as determined by the canvassing board."  This standard has been harshly criticized for being too vague and for leading to variations in standards across counties.  However, the Florida courts over the years have routinely refused to restrict the meaning of this statutory language.  Numerous states also use this same standard as the overruling guideline when manually reviewing ballots, including Texas thanks to a statute signed into law by Bush in 1997.

The attacks on this standard grew even sharper in the wake of the Florida Supreme Court's order to canvass all the undervotes statewide pursuant to the statutory standard.  However, that standard is the one found in Florida's Election Code that the Bush campaign says is immutable.  This position creates a Catch-22 for Florida.  If election officials do use the statutory standard, then they may be violating the 14th Amendment according to the Bush campaign because it is too liberal a standard.  However, if the courts try to change it or clarify it, then the Bush campaign would jump all over them for changing the election laws after the election (i.e., a violation of Title 3 Section 5 of the US Code).

For the more detailed answer, read these excerpts from Miami Herald article by Jay Weaver.

http://miamiherald.com/content/archive/news/elect2000/decision/104246.htm

Published Monday, December 11, 2000, in the Miami Herald

 Legal vote definition ignites debate

 BY JAY WEAVER

The seeming lack of a uniform standard for handling disputed ballots across Florida has become a paramount legal issue for the U.S. Supreme Court.

At the core of the controversy is a Florida law that says a legal vote is any ballot from which the voter's intent can be discerned. But state courts for years have been unwilling to say explicitly what that means.

And that has drawn the attention of the U.S. Supreme Court majority whose view may have been reflected in an opinion by Justice Antonin Scalia. He questioned whether presidential ballots that cannot be read by machine are legal votes and whether counting them might give the presidency to the wrong candidate.

More important, he implied that the standards for discerning voter intent vary so widely from county to county that they violate the equal protection clause of the U.S. Constitution.

The dilemma was clear Saturday, as each county's election officials, ordered by the Florida Supreme Court to hand count all ballots that showed no presidential vote, struggled with how to judge if a legal vote had been cast -- a pinpricked, dimpled or hanging chad?

Circuit Judge N. Sanders Sauls recused himself following the state Supreme Court's decision to reverse him, deliberately avoided spelling out specific guidelines for counting partially detached or dimpled chads on the so-called undervotes.

Lewis ordered that counters make a case-by-case decision on every ballot based on whether they could discern the voter's intent.

That decision was consistent with how state courts have been deciding issues of disputed ballots for a quarter of a century. The courts have generally been willing only to tell local canvassing boards to use their best judgment in following what state law has to say about disputed ballots.

The courts have found consistently that the point of state law is not to limit how voters express their preferences but to limit the canvassing board's ability to throw out ballots.

The law in question states that ``no vote shall be declared invalid or void if there is a clear indication of the intent of the voter as determined by the canvassing board.''

But Florida case law offers little specific guidance for local canvassing boards, which have broad discretion to authorize recounts and to gauge voter intent.

A 1975 Florida Supreme court case, Boardman vs. Esteva, which involved absentee ballots in Leon County, even warned against setting specific technical guidelines. Such guidelines, the court said, could work to disenfranchise voters, which is not the intent of state law.

``The right to vote is the right to participate; it is also the right to speak, but more importantly the right to be heard,'' the court said in Boardman.

The lack of a consistent policy for judging ballots that aren't read by machine may seem a major problem to some. But others argue that setting a policy that says only certain kinds of mismarked ballots can qualify as votes would limit the ability of voters to express their preferences.

Legal ballots rejected by machines, in the words of the state Supreme Court, ``may exist but have not been counted.''

Overall, the state's lack of specific guidelines for judging discarded ballots is also complicated by the different systems of voting county by county. While attention has been focused largely on the punch-style ballot machines in Miami-Dade and Palm Beach, most counties have optical scanners. One county still uses paper ballots.

Ultimately, determining voter intent has been left to local canvassing boards -- not unlike the broad authority of communities to define pornography in their midst.

That was emphasized by the majority of the Florida Supreme Court in its ruling Friday when it stressed the ``legislative emphasis on discerning the voter's intent is mirrored in the case law of this state and in that of other states.''