BANGKOK — 28 September 2026, Thailand’s Constitutional Court ruled on Monday that the use of barcodes and QR codes on ballot papers in the 8 February general election did not violate the Constitution, rejecting claims that the codes compromised the secrecy of voting.
The ruling means the election remains valid.
The court began oral deliberations at 09:30 on 28 September in a case referred by the Ombudsman following 22 complaints concerning the Election Commission’s organisation of the 8 February 2026 general election.
The complaints argued that barcodes and QR codes printed on ballot papers could potentially allow individual ballots to be traced back to voters, raising questions over whether voting had remained secret as required by the Constitution.
The court delivered its ruling at 14:00, with Election Commission chairman Narong Klanwarin among those attending to hear the decision.
The court said the central question was whether the use of QR codes and barcodes was compatible with the constitutional requirement that elections be conducted through direct and secret voting.
During the election, polling-station officials checked voters’ names, house-registration numbers, names, surnames and sex before voters signed the ballot stubs. Officials then detached the two ballot papers — one for constituency MPs and another for the party-list vote — and handed them to voters.
After marking their choices, voters folded the ballots and placed them in ballot boxes.
The petitioners argued that barcodes on party-list ballots and QR codes on constituency ballots could indirectly be used to trace a ballot back to an individual voter, particularly because the codes could be photographed or scanned during vote counting.
The Election Commission argued that this was not possible because voters’ names were not printed on ballots and ballot stubs were securely stored.
Evidence presented to the court showed that both barcodes and QR codes could be scanned using smartphones, but the resulting information consisted only of numbers or codes that would have to be combined with other documents before an individual voter could be identified.
Identifying a voter would require access to three separate sets of information: the ballot paper, its corresponding ballot stub and the voter register. Access to all three would generally not be possible without a court order.
For constituency ballots, scanning the QR code produces letters and numbers corresponding to the ballot booklet number. Each booklet covers 20 ballots.
The court found that this information alone could not be linked to a particular voter.
Party-list ballots, however, contained both QR codes and barcodes. The barcode at the bottom of the ballot contained information identifying the corresponding ballot booklet and could therefore potentially be matched with a ballot stub.
The court found that, if the ballot, stub and voter register were all combined, it could theoretically be possible to identify an individual voter.
It therefore considered whether security arrangements governing those documents were sufficient to protect ballot secrecy.
Ballots, ballot stubs and voter registers are handled under Election Commission regulations and retained for two years before ballots and stubs are destroyed.
At polling stations, the court acknowledged that election officials temporarily had access to the three types of documents. However, it said polling stations also contained security officers, voters and political party representatives, making any attempt to secretly match the documents difficult.
Officials were also required to promptly transfer election documents after polls closed.
Once documents reached district election authorities, they were stored more securely. Although some bags were not sealed with cable ties at that stage, they were placed inside outer bags signed by polling officials.
The large volume of ballots arriving from multiple polling stations also made matching individual ballots with particular voters difficult, the court said.
At provincial Election Commission offices, election documents were received separately from district election authorities, while voter lists came from local registrars. Documents were stored in sealed bags secured with cable ties and signed by polling officials, with ballot papers subject to an additional layer of storage.
The court found that these measures provided sufficient security and made unauthorised access to the ballots, stubs and voter registers difficult.
It also rejected arguments that an outsider could scan a barcode during vote counting and identify a voter.
Although scanning could reveal a ballot number corresponding to a particular stub, an outsider would still need access to the ballot stub and voter register. This would require cooperation from polling officials or district or provincial Election Commission officials and would constitute an illegal act.
The documents were also stored separately in ways that made it extremely difficult for outsiders to obtain all the information needed to identify a voter.
The court therefore found that election materials were protected by sufficient security measures and that identifying individual voters would be difficult.
Turning to the constitutional issue, the court said secret voting is intended to allow people to express their political choices freely, without intimidation, coercion or vote-buying.
If it were possible to trace a ballot back to an individual voter, the principle of secret voting would be undermined.
The court distinguished between absolute ballot secrecy, under which ballots contain no identifying codes whatsoever, and a system of conditional secrecy in which codes may be used for election administration and fraud prevention while access to information that could identify voters remains restricted.
It noted that completely identical, uncoded ballots could themselves create opportunities for electoral fraud.
The QR codes used on the ballots could not be used to trace an individual voter, the court found.
Barcodes, meanwhile, were intended to identify which batch a ballot belonged to, which polling station it had been assigned to and whether ballots had been improperly moved between constituencies. They could also assist investigations into alleged election fraud.
While barcodes on party-list ballots could theoretically be traced back through the combination of a ballot, stub and voter register, the court found that legal and physical safeguards prevented officials or voters from freely accessing all three sets of information.
An inspection of facilities where election materials were stored found that ballots, ballot stubs and voter registers were kept in accordance with regulations, with safeguards sufficient to prevent outsiders — as well as officials — from arbitrarily accessing and combining the documents to identify how an individual voted.
The court said barcodes also served legitimate purposes, including preventing counterfeit ballots, controlling the number of ballots issued, preventing ballots from being used in the wrong constituency and allowing ballots to be printed and distributed efficiently within limited timeframes.
Although other measures, including watermarks or QR codes, could potentially be used instead, the court found that barcodes were an effective method of controlling ballot papers and were not a disproportionate measure.
Balancing the competing considerations, the court said barcodes themselves did not reveal which candidate or party a voter had chosen. Identifying a voter would require combining three separate sets of protected documents.
As there was no evidence that such information had actually been linked in this way, the court found there was insufficient evidence to conclude that ballot secrecy had been compromised.
The use of barcodes and QR codes therefore did not violate the Constitution or infringe voters’ rights and freedoms.
However, the court said the Election Commission should maintain measures ensuring that ballots contain no markings or symbols capable of directly identifying voters and should continue strengthening safeguards for the storage of election materials.
