How does federalism complicate guarantees of personal rights?

Because Federalism make the government held the highest authority to create restrictions for the citizens.

Explanation:

Personal rights are rights that are given to us ever since we're born, and noone in this world should be able to take that away from us.

When we adopt a federalism as our system of government, it give the government representatives with the power to create Laws that the citizens have to obey under any circumstances.

When the law is essentially good for the people, this should possess no problem.

But there are cases when the government itself is so corrupt to the point where the laws that it makes actually harmed the citizens (such as North Korean's government who censored all citizens from saying bad things  about the government). This is where federalism could complicate the guarantees of personal rights

answer; when the government fails to protect the fundamental rights of the people;