Justice Stevens' plurality opinion starts by noting the rule laid down in the Court's poll tax cases (I'm omitting footnotes, citations, etc. as I go):

[E]ven rational restrictions on the right to vote are invidious if they are unrelated to voter qualifications.... [H]owever, we [have] confirmed the general rule that "evenhanded restrictions that protect the integrity and reliability of the electoral process itself" are not invidious ...Rather than applying any "litmus test" that would neatly separate valid from invalid restrictions, ... a court must identify and evaluate the interests put forward by the State as justifications for the burden imposed by its rule, and then make the "hard judgment" that our adversary system demands.

Justice Stevens then addressed the case at bar:

While petitioners argue that the statute was actually motivated by partisan concerns and dispute both the significance of the State's interests and the magnitude of any real threat to those interests, they do not question the legitimacy of the interests the State has identified.

+++

The first is the interest in deterring and detecting voter fraud. The State has a valid interest in participating in a nationwide effort to improve and modernize election procedures that have been criticized as antiquated and inefficient. [See National Commission on Federal Election Reform, To Assure Pride and Confidence in the Electoral Process 18 (2002) (with Honorary Co-chairs former Presidents Gerald Ford and Jimmy Carter).]

Justice Stevens quoted at length from that report, thus providing a rare example of such a bipartisan commission coming to some good (Justice Breyer would have placed equally strong weight on some of the commission's specific recommendations). He also cited the two recent federal enactments on voting procedures. He also noted that there was sufficient evidence that voter fraud happens to justify the state in trying to prevent it:

It remains true, however, that flagrant examples of such fraud in other parts of the country have been documented throughout this Nation's history by respected historians and journalists, that occasional examples have surfaced in recent years, and that Indiana's own experience with fraudulent voting in the 2003 Democratic primary for East Chicago Mayor - though perpetrated using absentee ballots and not in-person fraud - demonstrate that not only is the risk of voter fraud real but that it could affect the outcome of a close election.

There is no question about the legitimacy or importance of the State's interest in counting only the votes of eligible voters. Moreover, the interest in orderly administration and accurate recordkeeping provides a sufficient justification for carefully identifying all voters participating in the election process. While the most effective method of preventing election fraud may well be debatable, the propriety of doing so is perfectly clear.

+++

Judge Barker cited record evidence containing examples from California, Washington, Maryland, Wisconsin, Georgia, Illinois, Pennsylvania, Missouri, Miami, and St. Louis. The Brief of Amici Curiae Brennan Center for Justice et al. in Support of Petitioners addresses each of these examples of fraud. While the brief indicates that the record evidence of in-person fraud was overstated because much of the fraud was actually absentee ballot fraud or voter registration fraud, there remain scattered instances of in-person voter fraud. For example, after a hotly contested gubernatorial election in 2004, Washington conducted an investigation of voter fraud and uncovered 19 "ghost voters." ....After a partial investigation of the ghost voting, one voter was confirmed to have committed in-person voting fraud.

Soren Dayton has more on the East Chicago case, which resulted in 45 convictions. Turning to the challenge to the statute's requirements, Justice Stevens noted that some groups may be unduly burdened but found an insufficient basis to invalidate the entire statute on the record before the Court - thus leaving open the possibility of future challenges:

The burdens that are relevant to the issue before us are those imposed on persons who are eligible to vote but do not possess a current photo identification that complies with the requirements of SEA 483.16 The fact that most voters already possess a valid driver's license, or some other form of acceptable identification, would not save the statute under our reasoning in Harper, if the State required voters to pay a tax or a fee to obtain a new photo identification. But just as other States provide free voter registration cards, the photo identification cards issued by Indiana's BMV are also free. For most voters who need them, the inconvenience of making a trip to the BMV, gathering the required documents, and posing for a photograph surely does not qualify as a substantial burden on the right to vote, or even represent a significant increase over the usual burdens of voting.

Both evidence in the record and facts of which we may take judicial notice, however, indicate that a somewhat heavier burden may be placed on a limited number of persons. They include elderly persons born out-of-state, who may have difficulty obtaining a birth certificate; persons who because of economic or other personal limitations may find it difficult either to secure a copy of their birth certificate or to assemble the other required documentation to obtain a state-issued identification; homeless persons; and persons with a religious objection to being photographed. If we assume, as the evidence suggests, that some members of these classes were registered voters when SEA 483 was enacted, the new identification requirement may have imposed a special burden on their right to vote.

The severity of that burden is, of course, mitigated by the fact that, if eligible, voters without photo identification may cast provisional ballots that will ultimately be counted. To do so, however, they must travel to the circuit court clerk’s office within 10 days to execute the required affidavit. It is unlikely that such a requirement would pose a constitutional problem unless it is wholly unjustified. And even assuming that the burden may not be justified as to a few voters, that conclusion is by no means sufficient to establish petitioners’ right to the relief they seek in this litigation.

+++

Petitioners ask this Court, in effect, to perform a unique balancing analysis that looks specifically at a small number of voters who may experience a special burden under the statute and weighs their burdens against the State’s broad interests in protecting election integrity....But on the basis of the evidence in the record it is not possible to quantify either the magnitude of the burden on this narrow class of voters or the portion of the burden imposed on them that is fully justified.

+++

Finally we note that petitioners have not demonstrated that the proper remedy—even assuming an unjustified burden on some voters—would be to invalidate the entire statute. When evaluating a neutral, nondiscriminatory regulation of voting procedure, we must keep in mind that a ruling of unconstitutionality frustrates the intent of the elected representatives of the people.

Finally, Justice Stevens rejected the argument that the statute is improper because of a partisan motivation:

It is fair to infer that partisan considerations may have played a significant role in the decision to enact SEA 483. If such considerations had provided the only justification for a photo identification requirement, we may also assume that SEA 483 would suffer the same fate as the poll tax at issue in Harper.

But if a nondiscriminatory law is supported by valid neutral justifications, those justifications should not be disregarded simply because partisan interests may have provided one motivation for the votes of individual legislators.

Justice Scalia argued that the Court's precedents, the constitutional text and the practicalities of election litigation argued for a more sweeping rule deferring to state legislatures:

The lead opinion assumes petitioners' premise that the voter-identification law "may have imposed a special burden on" some voters... but holds that petitioners have not assembled evidence to show that the special burden is severe enough to warrant strict scrutiny, ... That is true enough, but for the sake of clarity and finality (as well as adherence to precedent), I prefer to decide these cases on the grounds that petitioners' premise is irrelevant and that the burden at issue is minimal and justified.

+++

The Indiana law affects different voters differently, ... but what petitioners view as the law's several light and heavy burdens are no more than the different impacts of the single burden that the law uniformly imposes on all voters. To vote in person in Indiana, everyone must have and present a photo identification that can be obtained for free. The State draws no classifications, let alone discriminatory ones, except to establish optional absentee and provisional balloting for certain poor, elderly, and institutionalized voters and for religious objectors. Nor are voters who already have photo identifications exempted from the burden, since those voters must maintain the accuracy of the information displayed on the identifications, renew them before they expire, and replace them if they are lost.

+++

This is an area where the dos and don'ts need to be known in advance of the election, and voter-by-voter examination of the burdens of voting regulations would prove especially disruptive. A case-by-case approach naturally encourages constant litigation. Very few new election regulations improve everyone's lot, so the potential allegations of severe burden are endless. A State reducing the number of polling places would be open to the complaint it has violated the rights of disabled voters who live near the closed stations. Indeed, it may even be the case that some laws already on the books are especially burdensome for some voters, and one can predict lawsuits demanding that a State adopt voting over the Internet or expand absentee balloting.

That sort of detailed judicial supervision of the election process would flout the Constitution's express commitment of the task to the States. See Art. I, §4. It is for state legislatures to weigh the costs and benefits of possible changes to their election codes, and their judgment must prevail unless it imposes a severe and unjustified overall burden upon the right to vote, or is intended to disadvantage a particular class. Judicial review of their handiwork must apply an objective, uniform standard that will enable them to determine, ex ante, whether the burden they impose is too severe.

(Italics in original).

Justice Souter's dissent complains about the absence of public transportation in Indiana and why the new requirements had to be phased in immediately.

UPDATE: Allahpundit looks at Justice Souter's argument that the travel time to the DMV imposes an unconstitutional burden on the right to vote:

Do note that if you take the left seriously here, the act of voting itself arguably imposes an unconstitutional burden: As with a trip to the DMV, it requires leaving work, traveling, and waiting on line for an unknown amount of time. The only difference between the two is having to scrounge around for a copy of your birth certificate.

(In fact, it was the Democrats who pushed for "motor voter" registration on the theory that registration at the DMV was a great convenience). And Michelle Malkin notes that one of the voters cited in the case as being disadvantaged by the law was herself illegally registered to vote in two states.

On December 9, 1981, between three thirty and four o'clock in the morning, Philadelphia Police Officer Daniel Faulkner made a traffic stop of a Volkswagen driven by William Cook, Abu-Jamal's brother, on Locust Street between 12th and 13th Streets, in Philadelphia. Officer Faulkner radioed for backup assistance, and both men exited their vehicles. A struggle ensued, and Officer Faulkner tried to secure Cook's hands behind his back. At that moment, Abu-Jamal, who was in a parking lot on the opposite side of the street, ran toward Officer Faulkner and Cook. As he approached, Abu-Jamal shot Officer Faulkner in the back. As Officer Faulkner fell to the ground, he was able to turn around, reach for his own firearm, and fire at Abu-Jamal, striking him in the chest. Abu-Jamal, now standing over Officer Faulkner, fired four shots at close range. One shot struck Officer Faulkner between the eyes and entered his brain.

Within a minute of Officer Faulkner's radio call, Officers Robert Shoemaker and James Forbes responded. Robert Chobert, a taxi cab driver who had just let out a passenger at 13th and Locust, stopped the officers before they arrived at the scene and notified them an officer had just been shot. Officer Shoemaker then approached the parked Volkswagen on foot and observed Abu-Jamal sitting on the curb. Despite Officer Shoemaker's repeated orders to freeze, Abu-Jamal did not remain still and reached for an object Officer Shoemaker could not yet identify. As Officer Shoemaker inched closer, he saw a revolver on the ground close to Abu-Jamal's hand. Officer Shoemaker kicked Abu-Jamal in the chest to move him away from the gun, and then kicked the gun out of Abu-Jamal's reach. Officer Shoemaker then motioned for Officer Forbes to watch Abu-Jamal while Shoemaker attended to Officer Faulkner. During this time, Officer Forbes also searched Cook, who had remained at the scene and was standing near the wall of an adjacent building. Cook made only a single statement: "I had nothing to do with it."

Additional officers arrived on the scene. Officer Faulkner was immediately rushed to Thomas Jefferson University Hospital, where he was later pronounced dead. Officers took Abu-Jamal into custody. He resisted arrest while officers moved him to a police van and tried to handcuff him. Abu-Jamal was also taken to Thomas Jefferson University Hospital. While Abu-Jamal was waiting for treatment in the emergency room's lobby, Priscilla Durham, a security guard on duty at the hospital, heard Abu-Jamal twice repeat, "I shot the motherf***er, and I hope the motherf***er dies." Officer Gary Bell also heard Abu-Jamal make this statement. Hospital personnel then took Abu-Jamal into the emergency room for treatment.

Officer Forbes recovered two weapons from the scene. A standard police-issue Smith & Wesson .38 caliber Police Special revolver, registered and issued to Officer Faulkner, with one spent Remington .38 special cartridge, was found on the street about five feet away from Officer Faulkner. Ballistic testing later confirmed the bullet that struck Abu-Jamal was fired from Officer Faulkner's revolver. A Charter Arms .38 caliber revolver containing five "Plus-P" high-velocity spent cartridges was found on the sidewalk near Abu-Jamal. Abu-Jamal had purchased this revolver in June 1979 and it was registered in his name. Officer Anthony Paul, supervisor of the Firearms Identification Unit in the Laboratory Division of the Philadelphia Police Department, testified at trial that the bullet recovered from Officer Faulkner's head was badly mutilated and could not be matched with a specific firearm. Officer Paul also testified that the recovered bullet specimen had eight lands and grooves with a right hand direction of twist, which was consistent with a bullet fired from a Charter Arms revolver.

The Commonwealth presented four eye-witnesses at trial. Cynthia White testified she saw Abu-Jamal run out of a parking lot on Locust Street as Officer Faulkner attempted to subdue Cook, and saw Abu-Jamal shoot Officer Faulkner in the back. She testified she then watched Officer Faulkner stumble and fall, and then saw Abu-Jamal hover over Officer Faulkner, shoot him a few more times at a close distance, and then sit down on the curb. Robert Chobert testified he heard a shot, looked up, saw Officer Faulkner fall to the ground, and then saw Abu-Jamal fire a few shots into Officer Faulkner. At the scene, Chobert identified Abu-Jamal as the person who shot Officer Faulkner. Michael Scanlon testified he witnessed an assailant, whom he could not identify, shoot Officer Faulkner from behind, then watched the officer fall, and saw the assailant stand over the officer and shoot him in the face. Albert Magliton testified he saw Abu-Jamal run across the street from the parking lot, then he heard shots and saw Officer Faulkner on the ground and Abu-Jamal on the curb. Magliton identified Abu-Jamal as the shooter, both at the scene and at trial.

On December 15, 1981, Anthony Jackson was appointed counsel for Abu-Jamal. Abu-Jamal was arraigned on charges of first degree murder and other related charges. The court granted Abu-Jamal's request to proceed pro se and the court designated Jackson, who had spent five months preparing for trial, as backup counsel.

A jury trial commenced on June 7, 1982. Abu-Jamal was disruptive, uncooperative, and hostile. He repeatedly insisted that John Africa, a social activist who was not a lawyer, be appointed as counsel, even after the court denied this request. Abu-Jamal's conduct necessitated his removal from proceeding pro se for the remainder of the trial, and at times caused him to be physically removed from the courtroom. The jury was instructed against drawing negative inferences from his removal. Jackson, who was present throughout the entire trial and was reinstated as primary counsel when Abu-Jamal was removed, kept Abu-Jamal fully informed throughout the proceedings.

During the lengthy trial, Jackson cross-examined each witness called by the prosecutor. Abu-Jamal presented seventeen witnesses: eight fact witnesses and nine character witnesses. Neither Abu-Jamal nor Cook testified at trial.

(Edited only for language). More on the case from the Faulkner family website here; press summary here.

Pray, if you will, for the repentance of Mr. Abu-Jamal, and his opportunity to seek God's forgiveness for what he has done and what he took from Officer Faulkner and his family. But no earthly justice can be done by allowing him to evade indefinitely the lawful and proper consequences of his crime.

The flaw in this argument is that, unlike the California primary, the I-872 primary does not, by its terms, choose parties’ nominees. The essence of nomination - the choice of a party representative - does not occur under I-872. The law never refers to the candidates as nominees of any party, nor does it treat them as such. ...

[R]espondents' assertion that voters will misinterpret the party-preference designation is sheer speculation. It "depends upon the belief that voters can be 'misled' by party labels. But '[o]ur cases reflect a greater faith in the ability of individual voters to inform themselves about campaign issues.'"... There is simply no basis to presume that a well-informed electorate will interpret a candidate's party-preference designation to mean that the candidate is the party's chosen nominee or representative or that the party associates with or approves of the candidate.... This strikes us as especially true here, given that it was the voters of Washington themselves, rather than their elected representatives, who enacted I-872.

(Citations omitted). Chief Justice Roberts, joined by Justice Alito, concurred but stressed a point touched on by the majority: that the issue of voter confusion really could not be assessed without examining the ballot, which has not been designed yet:

Voter perceptions matter, and if voters do not actually believe the parties and the candidates are tied together, it is hard to see how the parties' associational rights are adversely implicated. ...After all, individuals frequently claim to favor this or that political party; these preferences, without more, do not create an unconstitutional forced association.

...[T]here is no general right to stop an individual from saying, "I prefer this party," even if the party would rather he not. Normally, the party protects its message in such a case through responsive speech of its own.

Justice Scalia, joined by Justice Kennedy, dissented, arguing that the parties have to have greater control over their own message, including their membership, alluding even to the hot issues of the day:

The views of the self-identified party supporter color perception of the party's message, and that self-identification on the ballot, with no space for party repudiation or party identification of its own candidate, impairs the party's advocacy of its standard bearer. ...

...[T]hrusting an unwelcome, self-proclaimed association upon the party on the election ballot itself is amply destructive of the party's associational rights. An individual's endorsement of a party shapes the voter's view of what the party stands for, no less than the party's endorsement of an individual shapes the voter's view of what the individual stands for. That is why party nominees are often asked (and regularly agree) to repudiate the support of persons regarded as racial extremists.

Not only is the party's message distorted, but its goodwill is hijacked. There can be no dispute that candidate acquisition of party labels on Washington's ballot - even if billed as self-identification - is a means of garnering the support of those who trust and agree with the party. The "I prefer the D's" and "I prefer the R's" will not be on the ballot for esthetic reasons; they are designed to link candidates to unwilling parties (or at least parties who are unable to express their revulsion) and to encourage voters to cast their ballots based in part on the trust they place in the party's name and the party's philosophy.

...Is it enough to say on the ballot that a notorious and despised racist who says that the party is his choice does not speak with the party's approval? Surely not. His unrebutted association of that party with his views distorts the image of the party nonetheless.

...It is no mystery what is going on here. There is no state interest behind this law except the Washington Legislature's dislike for bright-colors partisanship, and its desire to blunt the ability of political parties with noncentrist views to endorse and advocate their own candidates. That was the purpose of the Washington system that this enactment was adopted to replace - a system indistinguishable from the one we invalidated in Jones, which required parties to allow nonmembers to join in the selection of the candidates shown as their nominees on the election ballot.... And it is the obvious purpose of Washington legislation enacted after this law, which requires political parties to repeat a candidate's self-declared party "preference" in electioneering communications concerning the candidate - even if the purpose of the communication is to criticize the candidate and to disavow any connection between him and the party.

It's a close case; Justice Scalia, as usual, has the firmest grasp of political theory and practice on the Court, although that doesn't necessarily mean that what is politically bad is also constitutionally bad; I think I would be inclined to side with the majority's view that as long as the ballot itself is not actively deceptive, the party's ability to engage in pre-election speech should be able to cure the possibility of a David Duke, a Lyndon LaRouche or an Al Sharpton hijacking its reputation and good name.

(Emphasis added, citations omitted). Justice Stevens, joined by Justice Souter, concurred with a note questioning the wisdom of the NY scheme. Justice Kennedy, joined by Justice Breyer, concurred with a lengthier ode to judicial independence:

When one considers that elections require candidates to conduct campaigns and to raise funds in a system designed to allow for competition among interest groups and political parties, the persisting question is whether that process is consistent with the perception and the reality of judicial independence and judicial excellence. The rule of law, which is a foundation of freedom, presupposes a functioning judiciary respected for its independence, its professional attainments, and the absolute probity of its judges. And it may seem difficult to reconcile these aspirations with elections.

Still, though the Framers did not provide for elections of federal judges, most States h