The bill to legalise euthanasia in the Netherlands was supported by a clear majority of the Dutch people and was easily passed in parliament.
It was formally approved by parliament's upper house on 10 April.
But not everyone agrees that humans should have the right to choose to die.
The Dutch Roman Catholic Church said the law would make it too easy for people to give up.
"People who are ill but consider themselves a burden to their family, that's the problem," said Peter van Zoest, spokesman for the Bishops Conference.
The main opposition Christian Democrats (CDA) and smaller Calvinist parties also opposed the law.
Andre Rouwoet, one of five MPs for the Christian Union, said his party believed life was a "God-given gift" and that people could not decide on their own death.
"The main objection of our party is that the idea of euthanasia, legalising euthanasia is based on the assumption of human autonomy, that every individual person can decide about his own life but also his death," he said.
One doctor at the German hospice foundation, Monika Schweihoff, said the Dutch plan was "appalling".
"The Netherlands is the first country to legalise euthanasia since the Nazis," she said in a statement.
"Euthanasia is not the only option - qualified hospice staff can also help terminally ill patients slip away painlessly."
Rita Marker, executive director of the International Anti-Euthanasia Task Force, said the law will send a dangerous signal "telling people that if it's legal, it's right."
"It will be like giving the household seal of approval," she said.
"What is currently a crime will be transformed into medical treatment."