If a Catholic lawyer represents a client in pursing a divorce, is he committing a sin?
No, why would you think so?
The Church requires a civil divorce if someone is seeking an annulment. Divorce is not a “sin”.
We cannot answer this. There is no blanket answer. It completely depends upon the actions the lawyer takes and **all **the factors of that **specific **divorce situation.
It is not inherently sinful to be a lawyer nor to represent a client in divorce proceedings.
In fact, it may be a moral and virtuous thing to do, even something that justice or charity demands, depending on the situation.
It may also indeed be sinful to participate in a divorce case depending on the situation.
Divorce most certainly is a sin, objectively. It is a sin against marriage, a sin against the sixth commandment.
It may not be a sin in some cases, even many cases, especially not a sin for the innocent spouse and not a sin for a spouse who must separate to protect him/herself, children, or in some cases property.
Isn’t it more correct to say that divorce is grave matter, which may or may not be a sin depending on the circumstances? Since the Church doesn’t recognize civil divorce, how can something it doesn’t juridically “see” and which is required for a Decree of Nullity be objectively a sin?
That is why I said it is a sin, objectively. Yes, grave matter would be accurate.
The Church certainly does recognize civil divorce as far as civil effects go.
Can. 1672 Cases concerning the merely civil effects of marriage belong to the civil magistrate unless particular law establishes that an ecclesiastical judge can investigate and decide these cases if they are done in an incidental or accessory manner.
As to the “requirement” of divorce for nullity: