Usage patterns
〈事〉は合法であるfor something to be legal
That transaction is legal.
合法的に〈動詞〉to do something in a legal manner
The company is operated legally.
〈事〉を合法化するto legalize something
Many countries have legalized marijuana.
合法な〈物〉a legal (means/way of doing something)
We should resolve the problem through legal means.