If a State signs but does not ratify a treaty, it is not legally bound by the treaty’s substantive obligations. However, under Article 18 of the Vienna Convention on the Law of Treaties (1969), the State must refrain from acts that defeat the object and purpose of the treaty, at least until it makes its intention not to ratify clear.

Legal Position Under International Law
1. Signing a Treaty
Signature expresses the State's preliminary consent to the treaty.
It shows an intention to examine the treaty domestically and consider ratification.
Signing does not create full legal obligations under the treaty.
2. Article 18 – Vienna Convention on the Law of Treaties (VCLT)
A State is obliged to refrain from acts which would defeat the object and purpose of a treaty when:
(a) It has signed the treaty, or
(b) It has expressed consent to be bound, but the treaty has not yet entered into force,
unless it has made clear its intention not to become a party.

So, signing a treaty creates a limited obligation — to not undermine the treaty before deciding on ratification.

3. No Binding Obligations Without Ratification
The treaty becomes binding only upon ratification (or equivalent act like accession).
The State can refuse to ratify without legal breach, unless it acts against the treaty’s purpose during the interim.

Practical Effect
The signing state:
Cannot claim full treaty rights or obligations.
It cannot violate the treaty’s core purpose until it decides to opt out formally.
Other States and international bodies may hold it politically or diplomatically accountable for contradicting the treaty’s principles.