Students with dyslexia will not be allowed to systematically use computers and adapted software in high schools.
The Council of States narrowly rejected a motion by Valais MP Sydney Kamerzin, overturning earlier approval by the National Council.
Supporters argued the measure would close a gap, as such tools are already permitted in primary school, lower secondary and at university.
Senator Fabien Fivaz questioned why students should lose access at a crucial stage.
Opponents in the upper chamber ultimately blocked the proposal by 21 votes to 19.
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