This is a complicated subject.

It all gets very complicated.

It was a very complicated vote.

The current situation is extremely complicated.

It is complicated and administratively difficult.

These are thus areas which require us to discuss the most intricate matters on a case by case basis.

Some of them are already involved and we want more of them involved, including the applicant countries.

Accounting firms were involved.

This subject is incredibly involved.

Women and children are involved.

I have consulted the services involved.

This is a very tricky business.

The question of age limits is extremely tricky.

He had a really very tricky subject to deal with.

A tricky situation has arisen within the industry in recent years.

They may have created tricky situations, individual problems that will have to be examined individually.