The court's ruling means Taiwan's parliament will have to amend existing laws or pass new legislation.
But it's still unclear how far parliament will go.
The LGBT community hopes legislators will simply amend the existing marriage laws to include same-sex couples, which would grant them the same rights enjoyed by opposite-sex couples, including in cases of adoption, parenting and inheritance - and making decisions for each other in medical emergencies.
However, they fear parliament won't do that and will instead pass a new law that recognises same-sex marriages but gives them only some rights, not equal treatment in all matters.
Religious and parents groups opposed to gay marriage say they will lobby parliament not to pass any laws on legalisation. They argue such an important matter that affects the whole of society shouldn't be decided by just a few grand justices, but by the people in a referendum.
Both sides will now focus their attention on persuading the legislators.