1. Adjective clauses are dependent clauses used to describe a noun. They often begin with que or quien. When using an adjective clause to describe something that the speaker knows exists, the indicative is used.

• Hay muchas personas que no votan.
• There are many people who don’t vote.
• Tenemos un gobierno que es estable.
• We have a government that is stable.

However, when using an adjective clause to describe something that the speaker does not know exists or believes does not exist, the subjunctive is used. The subjunctive is also used when the speaker does not have something specific in mind.

• Quiero tener un gobierno que sea fuerte pero justo.
• I want a government that is strong but fair.
• ¿Hay alguien a quien le motive la justicia?
• Is there anyone motivated by justice?
• No había nada que pudiéramos hacer.
• There was nothing we could do.

3. Some common verbs used with adjective clauses that can require either the subjunctive or the indicative are buscar, necesitar, and querer.

• Queremos un candidato que sea honrado.
• We want a candidate who is honest.
• Queremos al candidato que es honrado.
• We want the candidate who is honest.

In the first sentence the person does not have a specific person in mind and does not necessarily know if one exists (note the use of the indefinite article un), while in the second sentence he/she has a specific person in mind (using the definite article el).

When asking about the existence of something or someone, it is necessary to use the subjunctive as you do not know whether or not it exists.

• ¿Conocías a alguien que fuera abnegado?