Is it possible for my brother to pursue a double master's degree after completing his master's in political science in New Zealand?

Yes, your brother can pursue a second master's degree in New Zealand after completing his first master's in political science.

New Zealand universities generally allow students to enroll in multiple master's programs, as long as they meet the specific entry requirements for each course. Admission usually requires a relevant bachelor's or postgraduate degree with a good academic record.

For a second master's, your brother will need to apply for a Fee Paying Student Visa, which is typically granted for the course duration (up to four years, subject to change).

If he has already used a post-study work visa (PSW) after his first master's, he may not be eligible for another PSW after the second master's.