Is the word justificar the same in Brazilian and European Portuguese?

Yes

The word "justificar" is identical in both Brazilian and Continental Portuguese in terms of meaning, grammar, spelling, and core usage. The only differences lie in pronunciation.

In Brazilian Portuguese, the vowels are generally more "open" and the rhythm is more musical/syllable-timed; the unstressed "i" and "e" are clearly articulated. In Continental Portuguese, the rhythm is more stress-timed, and unstressed vowels are often "reduced" or almost swallowed (e.g., the "i" in "justificar" might be very short or nearly silent to an untrained ear).

Brazilian Portuguese Examples

1. Ele não conseguiu justificar o atraso. (He couldn't justify the delay.)
2. Vou justificar minha ausência com um atestado. (I will justify my absence with a medical certificate.)
3. Não tente justificar seu erro. (Don't try to justify your mistake.)
4. O professor pediu para justificar a resposta. (The teacher asked to justify the answer.)
5. Essa desculpa não justifica o que você fez. (That excuse doesn't justify what you did.)

Continental Portuguese Examples

1. Ele não conseguiu justificar o atraso. (He couldn't justify the delay.)
2. Tenho de justificar a minha falta com um atestado. (I have to justify my absence with a medical certificate.)
3. Não tentes justificar o teu erro. (Don't try to justify your mistake.)
4. O professor pediu para justificar a resposta. (The teacher asked to justify the answer.)
5. Essa desculpa não justifica o que fizeste. (That excuse doesn't justify what you did.)