The Supreme Court says states can force online shoppers to pay sales tax. The 5-4 ruling Thursday is a win for states, who said they were losing out on billions of dollars annually under two decades-old Supreme Court decisions that impacted online sales tax collection.

The high court ruled Thursday to overturn those decisions. They had resulted in some companies not collecting sales tax on every online purchase. The cases the court overturned said that if a business was shipping a product to a state where it didn't have a physical presence such as a warehouse or office, the business didn't have to collect the state's sales tax. Customers were generally supposed to pay the tax to the state themselves if they don't get charged it, but the vast majority didn't. Justice Anthony Kennedy wrote that the previous decisions were flawed.

"Each year the physical presence rule becomes further removed from economic reality and results in significant revenue losses to the States. These critiques underscore that the physical presence rule, both as first formulated and as applied today, is an incorrect interpretation of the Commerce Clause," he wrote.

In addition to being a win for states, the ruling is also a win for large retailers, who argued the physical presence rule was unfair. Retailers including Apple, Macy's, Target and Walmart, which have brick-and-mortar stores nationwide, generally collect sales tax from their customers who buy online. That's because they typically have a physical store in whatever state the purchase is being shipped to. Amazon.com, with its network of warehouses, also collects sales tax in every state that charges it, though third party sellers who use the site to sell goods don't have to.

But sellers that only have a physical presence in a single state or a few states could avoid charging customers sales tax when they're shipping to addresses outside those states. Online sellers that don't charge sales tax on goods shipped to every state range from jewelry website Blue Nile to pet products site Chewy.com to clothing retailer L.L. Bean. Sellers who use eBay and Etsy, which provide platforms for smaller sellers, also aren't required to collect sales tax nationwide.

Massachusetts' highest court on Monday struck down a proposed "millionaire tax" ballot question, blocking it from going before state voters in November and ending advocates' hopes for generating some $2 billion in additional revenue for education and transportation.

The Supreme Judicial Court, in a 5-2 ruling, said the initiative petition should not have been certified by Democratic Attorney General Maura Healey because it violated the "relatedness" clause of the state constitution that prohibits ballot questions from mingling unrelated subjects — in this case, taxing and spending.

The proposed constitutional amendment — referred to by its proponents as the "Fair Share Amendment," would have imposed a surtax of 4 percent on any portion of an individual's annual income that exceeds $1 million. The measure called for revenues from the tax to be earmarked for transportation and education.

Writing for the majority, Associate Justice Frank Gaziano said a voter who supported the surtax but opposed earmarking the funds for a specific purpose would be left "in the untenable position of choosing which issue to support and which must be disregarded."

The justices offered hypothetical examples of voters who might support spending on one priority but not the other, such as a subway commuter with no school-age children.

The measure had been poised to reach voters in November after receiving sufficient support from the Legislature in successive two-year sessions. But several business groups, including the Massachusetts High Technology Council and Associated Industries of Massachusetts, sued to block it.

The court's ruling was a devastating blow for Raise Up Massachusetts, a coalition of labor unions, community and religious organizations that collected more than 150,000 signatures in support of the millionaire tax.

Massachusetts' highest court is expected to rule on whether a proposed "millionaire tax" can go before state voters in November.

The Supreme Judicial Court is poised to issue its decision Monday after weighing the case for several months. The proposed constitutional amendment would impose a surtax of 4 percent on any portion of an individual's annual income that exceeds $1 million. The measure calls for revenues from the tax to be used for transportation and education.

Several business groups sued to stop the proposed surtax from appearing on the ballot, claiming it violates constitutional restrictions on ballot questions.

The Raise Up Massachusetts coalition collected more than 150,000 signatures in support of the measure and estimates it would raise nearly $2 billion in additional taxes annually for the state.

The Supreme Court sounded concerned Tuesday about doing away with a rule that has meant shoppers don't always get charged sales tax when they hit "checkout" online.

The justices were hearing arguments in a case that deals with how businesses collect sales tax on online purchases at sites from Amazon.com to Zappos. Right now, under a decades-old Supreme Court rule, if a business is shipping a product to a state where it doesn't have an office, warehouse or other physical presence, it doesn't have to collect the state's sales tax. Customers are generally supposed to pay the tax to the state themselves if they don't get charged it, but the vast majority don't.

More than 40 states have asked the Supreme Court to abandon its current sales tax collection rule , saying that as a result of it and the growth of internet shopping, they're losing billions of dollars in tax revenue every year.

But several Supreme Court justices suggested during arguments Tuesday that they had concerns about reversing course.

"I'm concerned about the many unanswered questions that overturning precedents will create a massive amount of lawsuits about," Justice Sonia Sotomayor told South Dakota Attorney General Marty Jackley, who was arguing for the court to do away with its current rule.

Chief Justice John Roberts pointed to briefs suggesting the problem of sales tax collection "has peaked" and may be "diminishing rather than expanding." ''Why doesn't that suggest that there are greater significance to the arguments" that the court should leave its current rule in place, he asked.

The fact that Congress could have addressed the issue and has so far hasn't, Justice Elena Kagan said, "gives us reason to pause." Congress can deal with the issue in a more nuanced way than the court, she said, saying Congress is "capable of crafting compromises and trying to figure out how to balance the wide range of interests involved here."

Large retailers such as Apple, Macy's, Target and Walmart, which have brick-and-mortar stores nationwide, generally collect sales tax from their customers who buy online. But other online sellers that only have a physical presence in a few states can sidestep charging customers sales tax when they're shipping to addresses outside those states.

Online shoppers have gotten used to seeing that line on checkout screens before they click "purchase." But a case before the Supreme Court could change that.

At issue is a rule stemming from two, decades-old Supreme Court cases: If a business is shipping to a state where it doesn't have an office, warehouse or other physical presence, it doesn't have to collect the state's sales tax.

That means large retailers such as Apple, Macy's, Target and Walmart, which have brick-and-mortar stores nationwide, generally collect sales tax from customers who buy from them online. But other online sellers, from 1-800 Contacts to home goods site Wayfair, can often sidestep charging the tax.

More than 40 states are asking the Supreme Court to reconsider that rule in a case being argued Tuesday. They say they're losing out on "billions of dollars in tax revenue each year, requiring cuts to critical government programs" and that their losses compound as online shopping grows. But small businesses that sell online say the complexity and expense of collecting taxes nationwide could drive them out of business.

Large retailers want all businesses to "be playing by the same set of rules," said Deborah White, the president of the litigation arm of the Retail Industry Leaders Association, which represents more than 70 of America's largest retailers.

For years, the issue of whether out-of-state sellers should collect sales tax had to do mostly with one company: Amazon.com. The online giant is said to account for more than 40 percent of U.S. online retail sales. But as Amazon has grown, dotting the country with warehouses, it has had to charge sales tax in more and more places.

President Donald Trump has slammed the company, accusing it of paying "little or no taxes" to state and local governments. But since 2017, Amazon has been collecting sales tax in every state that charges it. Third-party sellers that use Amazon to sell products make their own tax collection decisions, however.

The case now before the Supreme Court could affect those third-party Amazon sellers and many other sellers that don't collect taxes in all states — sellers such as jewelry website Blue Nile, pet products site Chewy.com, clothing retailer L.L. Bean, electronics retailer Newegg and internet retailer Overstock.com. Sellers on eBay and Etsy, which provide platforms for smaller sellers, also don't collect sales tax nationwide.

States generally require consumers who weren't charged sales tax on a purchase to pay it themselves, often through self-reporting on their income tax returns. But states have found that only about 1 percent to 2 percent actually pay.

Retailers are hoping for a resolution this year from the Supreme Court, which hears arguments Tuesday in a decades-old dispute: Whether companies must collect sales tax on items sold in a state where they don't have a store or other building.

If the court backs government officials who say they're losing billions of dollars in uncollected taxes, thousands of small companies could be forced to start charging their out-of-state customers for them. Some businesses fear that could alienate customers used to tax-free shopping. On the other side: Retailers who do collect sales tax and believe those who don't have an unfair advantage.

The justices will hear online retailers Wayfair, Overstock.com and Newegg challenging a South Dakota law enacted last May requiring out-of-state retailers that have sales of more than $100,000 or over 200 transactions a year in the state to collect sales tax. Their decision could have national implications on e-commerce, although Congress can pass legislation afterward that broadens or narrows the law.

The Supreme Court agreed Friday to wade into the issue of sales tax collection on internet purchases in a case that could force consumers to pay more for certain purchases and allow states to recoup what they say is billions in lost revenue annually.

Under previous Supreme Court rulings, when internet retailers don't have a physical presence in a state, they can't be forced to collect sales tax on sales into that state. Consumers who purchase from out-of-state retailers are generally supposed to pay the state taxes themselves, but few do. A total of 36 states and the District of Columbia had asked the high court to revisit the issue.

Large brick-and-mortar retailers like Walmart and Target have long bemoaned the fact that they have to collect sales tax on online purchases because they have physical stores nationwide. Meanwhile, smaller online retailers, who don't have vast networks of stores, don't have to collect the tax where they don't have a physical presence.

Internet giant Amazon.com fought for years against collecting sales tax but now does so nationwide, though third-party sellers on its site make their own decisions. But the case before the Supreme Court does directly affect other online retailers, including Overstock.com, home goods company Wayfair and electronics retailer Newegg, who are part of the case the court accepted.

States say the court's previous rulings have also hurt them. According to one estimate cited by the states in a brief they filed with the high court, they'll lose out on nearly $34 billion in 2018 if the Supreme Court's previous rulings stand. The Government Accountability Office, which provides nonpartisan reports to Congress, wrote in a report last year that state and local governments would have been able to gain between $8.5 billion and $13 billion in 2017 if they could require out-of-state sellers to collect tax on sales into the state. All but five states charge a sales tax.