Authorities in Missouri executed an inmate on Tuesday night, making him the first person put to death by a state since the U.S. Supreme Court weighed in on lethal injection last month.

Missouri and Texas have combined to carry out nearly all of the executions in the United States this year, and both states had lethal injections scheduled scheduled to take place over a three-day span this week.

David Zink, who was convicted of murdering Amanda Morton in 2001, had appealed to the Supreme Court, arguing that there were issues with the lawyers he was assigned before representing himself. In a series of orders on Tuesday, the court declined to stay his execution; the justices offered no explanations and there were no recorded dissents.

According to an outline of the case from the Missouri Supreme Court, which declined to get involved, Zink told investigators he killed Morton, saying he rear-ended her car, strangled her and stabbed her neck. The court also said she had “between 50 and 100 blunt force injuries” and described evidence that Morton was sexually assaulted.

In filings to the Supreme Court, Zink’s attorneys also argued against the death penalty’s constitutionality. They pointed to a recent dissent from two justices who questioned whether the death penalty was constitutional, going on to argue that capital punishment “has become a source of error and bias.” The office of Missouri Attorney General Chris Koster dismissed this argument in its own filing.

Zink was executed by lethal injection at 7:33 p.m. local time in Bonne Terre, Mo., and pronounced dead at 7:41 pm., according to the Missouri Department of Corrections.

On Thursday, meanwhile, Texas plans to execute Clifton Williams, who was convicted of stabbing, beating and strangling a 93-year-old woman, according to state officials.

Zink’s execution marks the country’s first since the Supreme Court said last month that a drug used in troublesome lethal injections could be used going forward. However, this is a very different situation than we saw the last time the Supreme Court upheld a lethal injection policy, which took place nearly a decade ago amid a very different landscape for capital punishment in this country.

When the justices upheld a three-drug combination as constitutional in 2008, they also ended a de facto moratorium and allowed executions to resume (which they quickly did, as six states carried out executions in the weeks following that ruling). But there has been no such nationwide moratorium this time around, because so much changed between the 2008 decision on lethal injection and ruling to follow in 2015.

In 2008, the justices were discussing a three-drug method used commonly across the country. There was more (relative) uniformity to the way executions were carried out. Lethal injection was the primary method of execution, and lethal injections usually involved three drugs: an anesthetic, a paralytic and a drug to stop the heart.

But the years that followed saw chaos slowly and then abruptly break out in this system. An ongoing shortage of the key lethal injection drugs prompted states to turn to different combinations and other methods, which eventually caused some to try new and untested combinations.

In three states — Ohio, Oklahoma and Arizona — executions involving the sedative midazolam appeared to go awry last year, with inmates gasping, choking and remaining conscious for longer than intended. The most high-profile of these involved the Oklahoma inmate Clayton Lockett, who kicked, bucked his body and grimaced during his execution in April 2014.

Widespread criticism followed, as did a state investigation that placed the blame on members of the execution team failing to properly place an intravenous needle that would deliver the drugs. More than eight months later, Oklahoma resumed executions, putting Charles Warner — a man convicted of raping and murdering an infant — to death using a larger doze of midazolam.

Four Supreme Court justices said they would have stopped that execution, questioning whether midazolam could be used to properly sedate inmates during executions. The following week, the court decided to hear a challenge to Oklahoma’s policy.

Yet while executions in Oklahoma, Florida and Alabama were stayed — because the states all use or, in Alabama’s case, intended to use midazolam — other states said they did not intend to delay their executions. A spokesman for the Texas Department of Criminal Justice noted that the state used a single dose of pentobarbital for executions, noting at the time that it had used the protocol dozens of times since 2012 “without complication.”

So in the months since the Supreme Court said it would hear the lethal injection challenge, heard that challenge and issued a ruling on said challenge, Texas has executed eight inmates and Missouri has executed four.

In Georgia, authorities planned to execute an inmate during this window, but they have indefinitely delayed it. This execution was postponed once due to a winter storm, then called off a second time days later due to issues with the lethal injection drugs. (Georgia later said the problem was that the drugs were being kept too cold.)

Meanwhile, officials in Florida, Alabama and Oklahoma have all called for their states to resume executions now that the Supreme Court has ruled. Unlike Texas and Missouri, these pushes were a direct response to the Supreme Court, which ruled 5 to 4 that the use of midazolam was constitutional.

Including Zink, 18 inmates have been put to death so far this year.

[This post has been updated.]