The Supreme Court Gets it Wrong.

In no particular order:

Dred Scott was born a slave in Virginia before 1800.  He was sold several times, and in 1838, he and his wife were sent from a free territory in what is now Minnesota to Louisiana, a slave state.  They traveled on their own and were on a Mississippi River boat in what was then the Free State of Iowa, when a daughter was born.  By law, the daughter was therefore free.  Scott sued to free the whole family and was denied.  They were sold again to a New York (a free state) owner and Scott sued again. The case rose to the supreme court, which nonsensically decided in 1857 that Scott was not really a citizen, that the 5th amendment banned property from being taken without due process and several other dubious rulings, and overturned the Missouri Compromise, effectively allowing slavery in all states.  President Buchanan had illegally persuaded at least one northern justice to vote with the southerners.  The ruling was eventually overturned, (not the least by the 13th amendment), but not before it had become a major provocation for the Civil War.

Bush v Gore.  The popular vote in the election of 2000 was won fairly convincingly by Gore, but the vote in the electoral college was close.  In Florida, the count was extremely close: at the completion of the first count, Bush had a 537 vote lead of almost 6 million cast.  There was an enormous amount of election fraud and corruption committed by Republicans: the Secretary of State, responsible for the count, was Bush's campaign manager for the state.  The governor was his brother, tens of thousands of mostly Democratic voters had been suppressed by caging, 50,000 mostly black voters were purged on the grounds that they were felons when they were not, a republican operative had switched parties to participate in the committee to design the infamous "butterfly" ballot, leading at least 3000 people to vote for third party candidate Buchanan who meant to vote for Gore, and hundreds more voted for both, invalidating their ballot. Republican operatives screaming in the ear of pollworkers trying to do a recount.  The state supreme court tried to support a recount but the US supreme court blocked it, going back and forth several times until it was finally too late and no recount could be completed in time.  The president that the court selected proceeded to nominate two even worse justices to the court, abandon the antiterrorism work started by his predecessor and rejected warnings by the CIA of what would be the worst terrorist (or military) attack in US history, start an unprovoked war, and wrecked the economy.

Jones v Clinton  Paula Jones claimed that Bill Clinton had sexually harassed her while he was governor of Arkansas. The court ruled that Clinton, while he was serving as president, could be required to testify in a civil suit against him, even though the constitution exempts him from legal action while he is serving, claiming that it shouldn't particularly interfere with his ability to serve his duty as president.  In fact, although he was cleared of any wrongdoing in the Jones case, he spent most of the next two years dealing with the consequences of this testimony, including impeachment.

DC v Heller.  The District of Columbia had long required that all firearms be licensed and be stored unloaded.  In 2008, the court took the extraordinary position that the bit about militias in the second amendment is irrelevant to the the right of individuals to keep and bear arms, despite extensive writings by the founders that the militias are the whole point of it.  Only the requirement that guns be stored unloaded or disassembled was overturned; it didn't really affect DCs right to regulate, but now that the precedent that the comma in the second amendment should be taken as a period has been established, we can be sure another bad decision will follow.

Citizens United vs FEC.  Citizens United made an attack movie against Hilary Clinton, which they advertized on TV during the 2008 election cycle, showing many of their criticisms of the candidate in the ads.  Because CU's funding is secret (it apparently comes from the Koch brothers), FEC ruled that this was a violation of the Tillman Law of 1907 blocking corporate donations to candidates.  The court decided, against more than a century of explicit law and overwhelming precedent and evidence, that corporate political advertising is protected free speech, effectively overturning Tillman.

Buckley v Valeo.   In 1974, congress passed a law putting various specific limits on political contributions.  The court struck down a number of those limitations, for the first time equating money and free speech and opening the door to subsequent even more consequential rulings, such as Citizens United and McCutcheon v FEC, which ruled that aggregate limits to campaign contributions are illegal.

Look, the employees and owners of a corporation are actual people, and under Tillman, have a right to donate to political causes.  But corporations are not.  They have no morality or sense of fairness, they have very narrow short term goals, and they often have lots of money.  In a century or so, when the history of the American collapse into corruption is written, this group of decisions will be recognized to have been a big part of why.

Plessy v Ferguson.  By a 7-1 majority, the court of 1896 upheld states laws requiring racial segregation in such contexts as streetcars, schools, drinking fountains, etc., defining a doctrine which came to be called "Separate but equal", and cementing another half century of segregation and discrimination.  The nonwhite services were invariably not equal, until this decision was overturned by Brown v Board of Education in 1954.

Shelby Co v Holder.  One of the outgrowths of the Brown v Board of Education decision was the Voting Rights Act, which was passed by overwhelming majorities in congress in 1965 and repeatedly renewed by similar majorities.  Certain regions had a history of laws blocking minorities from voting, and in those regions, explicitly listed in the act, the justice department had to review all laws affecting voting.  Shelby County, Alabama, wanted to install new, but more subtle and not racially explicit versions of the racially discriminatory policies of old, but they were blocked by the VRA.   So Shelby sued. The court upheld most of VRA, except struck down the classification of states and regions, saying the 40 year old classifications had no logical relationship to the present day facts.  Which plainly ignored the fact that Shelby was trying to do exactly what the law had originally been intended to block.  The court pointed out that congress could make adjustments to the classifications and restore the law Within hours of the ruling, several states had passed into law voting restrictions which had been previously been blocked by VRA.

Marquette Nat. Bank of Minneapolis v. First of Omaha Service Corp.    First of Omaha wanted to sell credit cards to customers in Minnesota, and Nebraska had a higher maximum interest rate  (16%) than Minnesota (8%), which meant that FoO could profitably reach customers that banks in Minnesota could not.  The Supreme Court, in 1978, unanimously agreed with FoO; that lenders should be allowed to charge whatever interest rate pertains in their home state.  Remarkably quickly, many banks had moved their legal home state to South Carolina,  Nevada and a few others, which have NO legal maximum interest rate on loans and the local banks offering low interest largely evaporated.  Not long after, the payday loan industry was created, all chartered in the same places despite doing business all over the country.   300% interest is commonplace and rates in excess of 1000% have been observed.

McCarran-Ferguson Act.  In a case that went before the court in 1944, Southeast Underwriters Association was found  to be a monopoly, using boycotts, intimidation, and other coercive tactics to maintain its 90% market share in the region, despite gouging and other non-competitive behavior, in clear violation of the Sherman Anti-Trust Act.  The insurance company had questioned whether the Federal Government's jurisdiction applied over a regional insurance company.  The court correctly said yes.  Congress, led by two of the most corrupt senators in history, almost immediately passed a law that specifically exempted the insurance business from most anti-trust regulation on the bizarre grounds that it's somehow not interstate commerce, but allowing states to regulate on their own.  Many did, but the monopoly power of the insurers generally exceeded the enforcement power of the states.   For example, in 1999 Washington State tried to block insurers from cancelling healthcare policies due to pre existing conditions, but was forced to back down by a boycott.   The McCarran-Ferguson act and the unregulated trusts it allowed are directly responsible for much of the high price and poor behavior of insurance in the US.

Korematsu.  Two and a half months after the Japanese sneak attack on Pearl Harbor, President Roosevelt signed executive order 9066, ordering Japanese Americans into internment camps, regardless of citizenship. Fred Korematsu, a 23 year old welder born in Oakland, CA, refused to obey, claiming the order was unconstitutional.  Two years later, his challenge made it to the supreme court which decided against him, though admitting that the internments were "constitutionally suspect" but justified by the war.  This decision is technically still valid although most legal scholars recognize that it was an error.

addenda: 27 Jun 2018
Trump v Hawaii  During his presidential campaign, Trump repeatedly railed incoherently about Muslims and promised to ban them from entering the country, irrespective of reason, security status, etc.  A week after he was inaugurated, he signed an executive order implementing this.  It was immediately challenged in court and blocked by every real court that looked into it.  Several adjustments to the order later, the Roberts court allowed the ban to take place, arguing illogically that despite repeated insistence by Trump that it is a Muslim travel ban, that it wasn't.

Janus v AFSCME  For decades, once a shop has voted to unionize, all workers are required to pay union dues, whether they support the union or not.  The rationale is that all workers are benefiting from the work the union does, and might be called upon to do, much as you are required to have auto insurance in case you get into an accident.   The court has now ruled, explicitly contradicting an earlier ruling, that government workers don't have to pay their dues if they don't want to. Several states already have laws doing this for private industry, cynically called "Right to Work" laws.

addenda: 25 Jun 2022

Dobbs v Jackson.  The state of Mississippi made a law that banned most abortions after 15 weeks, a restriction deemed too narrow under the 1973 Roe vs Wade ruling, which had been repeatedly upheld despite numerous challenges.  In 2022, the court ruled, in a vast overreach of the needs of the case and in at least 4 cases, the explicit assurances in their confirmation hearings that Stare Decisis prevented it, that Roe vs Wade was, in fact, unconstitutional.

references:
http://www.newsreview.com/reno/top-10-worst-supreme-court/content?oid=5378990
http://www.time.com/time/specials/packages/completelist/0,29569,2036448,00.html