Legal Question in Civil Litigation in Massachusetts

I admire your perseverance in planning to defend yourself at trial. The short answer is, 'yes,' you CAN subpoena witnesses from the other side (or anyone really), but should do so more than 7 days before the trial begins. If it is less than 7 days away, you might go ahead and subpoena witnesses anyway, but might need to fend off an attack by the other side that the subpoenas were untimely and the witrnesses (even if they show up) should not be permitted to testify.

Your pro se status might help you here( but not necessarily). Argue any witnesses who actually show were not prejudiced by short notice, the evidence of this is that they showed up to testify. So the judge should let them do so. No harm no foul here.

However, think carefully about WHO you intend to subpoena and why. Is the person the most knowledgable, appropriate one to provide the testimony you seek? Or should you have subpoenaed someone else? If someone else knows better/more, the witness you sought may be deemed incompetent to testify or his/her testimony irrelevant to the issues being tried. Only subpoena absolutely essential witnesses and know why you want them to testify for you at trial.

General advice: Don't waste time or lose focus. Always be polite, respectful of others and do not interrupt (or do so minimally). Keep things simple, thoughtful and direct and you will likely fare better than worse.

Good luck.