I don't mean to reopen this thread. James K answer is perfectly acceptable but as in so many other controversies one related to the subject of your question has also made a trip to the European Court last year (2017).
The court ruled that vaccines can be blamed for causing illnesses even if there is no [direct] scientific proof. This does not imply absence of evidence. In the press release the following was mentioned:
Where there is a lack of scientific consensus, the proof of the defect
of the vaccine and of a causal link between the defect and the damage
suffered may be made out by serious, specific and consistent evidence.
The temporal proximity between the administering of a vaccine and the
occurrence of a disease, the lack of personal and familial history of
the person vaccinated and the existence of a significant number of
reported cases of the disease occurring following such vaccines being
administered may, where applicable, constitute sufficient evidence to
make out such proof.
As you can probably guess this raised alarms everywhere (Science Magazine):
Did the European Union’s highest court just deal a blow to science?
"Vaccines can be blamed for illness without scientific proof," read
many headlines about the European Court of Justice’s (ECJ’s) ruling on
the case of a French man who claimed that a hepatitis B vaccine caused
his multiple sclerosis (MS). Alarmed experts pointed out that no link
between the vaccine and MS has ever been established and fretted that
the Luxembourg-based court had opened the floodgates to large numbers
of spurious lawsuits.
But the Court decision, while shocking when you first ear it, is not that unreasonable. Finding direct scientific evidence of the association between a vaccine and a disease puts an impossible burden on the complainer. What the court decided was that when credible evidence (not proof) is presented the blame can be made. As explained by others (Nature):
The ECJ's judgment said that EU laws do not stop courts from
considering "serious, specific and consistent" circumstantial evidence
in such cases, alongside scientific evidence.
The court emphasized that liability claims for vaccine harm must be
considered on a case-by-case basis. It also ruled that the burden of
proof remained on plaintiffs (the man's family, in this case) and that
courts must consider relevant evidence from medical research. These
caveats are important, says Alex Stein, an expert in civil liability
law and medical evidence at Brooklyn Law School in New York. "Under
this framework, credible medical evidence showing that the vaccine is
safe will win the case," he says. "Those who say that the ECJ decision
has opened a floodgate for multiple vaccine liability suits are
The judgment does not mean that vaccines can be blamed for illness
without scientific evidence, or that spurious cases can win when the
scientific evidence is against them, says Stein. Vaccine makers, as
defendants, will ensure that courts hear the most compelling medical
evidence in their favour, he adds.
This obviously has an impact in the current debate between pro and against vaccine movements. And certainly the increasing number of deaths due to measles outbreaks in Romania does not help. But accordingly to the European Court not only can people speak against vaccines, they can sue the producers of these vaccines (however not be mistaken by an act of Defamation which has a fully separate legal framework).
Perhaps is for the best. This, like many other subjects, should be decided considering arguments, not laws. And it might even lead to a better regulation over vaccination.