I bought one-stop flight that switches in the USA, and my lawyer told me it's not allowed because I might run-away during the stop.

It cut off my question on the title: "Is it true that you are not allowed to buy a one-stop flight ticket (that switches the plane in USA) while you are on voluntary departure?"

Well, is that what you intend to do? I don't think there are restrictions unless the court thinks you may be a flight risk, then your lawyer is probably correct.

I'm a risk-free immigrant according to the USA documents. Is one-way ticket allowed in this circumstances?

it cut off my question on the title:

It cut off your question because the title is not where you ask your question. The title is for a brief description of your question. I.E. Customs and flights stopping over.

I don't think it is true. If you are not changing planes, then you would just not be allowed off the plane. International flights require that deplaning passengers go through customs.

But its easy to find out, call the airline.

I'm a risk-free immigrant according to the USA documents. Is one-way ticket allowed in this circumstances?

If that is the case then you are not a flight risk, but why has your counsel said you can't.

If that is the case then you are not a flight risk, but why has your counsel said you can't.

I have no clue, I'm just trying to figure out what's true or not since I have already bought the ticket and I can get it refund.

*Can't

It depends on type of visa you use to enter US. Holders of B1/B2 are normally asked to see if they have return ticket.