After a series of accidents on the MBTA, including a fire on the Orange Line last week which caused a chaotic evacuation but no injuries, GBH News legal analyst and Northeastern University law professor Daniel Medwed spoke with Morning Edition hosts Paris Alston and Jeremy Siegel about the T’s legal liabilities. This transcript has been lightly edited.

Paris Alston: How easy is it to even sue the T? Because aren't there restrictions on suing government agencies most of the time?

Daniel Medwed: Yes, that's right. So on the one hand, there are barriers to filing lawsuits against public, state and local entities based on this long-standing concept known as sovereign immunity — that the king, the crown, the government, can't do harm, that they represent all of us. But on the other hand, Massachusetts, like virtually every state that I'm aware of, has a specific law in place that governs when you can file these suits in precise circumstances. It's called the Massachusetts Tort Claims Act. And the word tort, it's not a fancy pastry. It's the legal term for a personal injury or property damage action.

Jeremy Siegel: So what do you have to prove in order to file a lawsuit against our king, our crown, the MBTA, under that act?

Medwed: Basically, as a threshold matter, you have to prove negligence: That some member of the T, some public employee, exercised care at a level below the standard of reasonableness. In other words, negligence is a way to make someone accountable in court — even if they don't hurt you intentionally or recklessly, but they simply don't satisfy the minimum level of care that we expect them to achieve when performing their tasks. So maybe a bus driver who speeds on a crowded street, a train that falls apart because of poor maintenance, something like that. And because the T charges money to transport members of the public, under state law it's considered a common carrier, which means that its employees are held to a slightly higher standard of care than the average private driver.

Alston: Coming to mind for me is the family of Robinson Lalin, the man who was killed on the Red Line a few months ago. And you mentioned that there's a time period before they would actually be able to sue. So in that case, though, who technically gets sued under this law? Is it the employee who caused the injury or, in that case, the death? Is that the MBTA itself or is it both?

Medwed: The law is very clear on this: You would sue the T itself. In other words, under the Tort Claims Act, you can sue a public employer based on the actions of a public employee. And generally that employee is immune from an individual lawsuit so long as her behavior occurred within the scope of her job and she didn't cause the harm intentionally. In legal circles, this is known as respondeat superior, that the principal is responsible for the actions of the agent. It's sometimes also called, in a less fancy term, derivative liability — that an employer's liability derives from the working relationship with the employee.

Siegel: In addition to showing negligence on the part of a T employee, what are some of the other hurdles you might have to clear to get to court in one of these cases?

Medwed: I think the biggest hurdle is timing. There's a very specific procedure that differs from run-of-the-mill tort cases for instigating a lawsuit against a public entity. You have to present your claim in writing to the executive agency, to the T, within two years of the accident. And then the T has six months to respond, typically by denying the allegations, after which you basically have to rush to court and file your lawsuit within three years from the incident.

This is different from regular cases, which means that it's a trap for the unwary, for an unsophisticated litigant, or for an inexperienced lawyer who doesn't know how to handle Tort Claims Act cases. Before I was preparing for this segment, I didn't know about some of these precise procedures at all. So you could really see how some people might be time-barred. Good old Charlie, who is lost on the MTA and riding around the streets of the Boston, his fate unknown — that famous song that you guys may know — is probably out of luck. He's probably time-barred under the Mass Tort Claims Act.

Alston: Assuming you're able to weave through all of those obstacles and you can show negligence by a T employee, and you present that claim to the agency within that two year period, how much money could you actually get?

Medwed: Not as much as one might think, especially after there were some amendments to this law around 2010. First of all, you can't get, under any circumstances, what are called punitive damages. That means a jury can award extra damages to you based on the desire to punish the T, the defendant, for egregious misconduct. You just can't get punitive damages. Second, there's a cap on the amount of compensatory damages, the amount of money you can get to compensate or cover for your actual injuries. That cap is $100,000. But get this, there is an exception just for the T, only the MBTA, not other public agencies. If the T causes you a serious bodily injury, which could be disfigurement, or losing a limb, or death, then the $100,000 cap doesn't apply and you could receive more in compensation.

Siegel: Let's talk about that incident on the Orange Line last week, the fire over the Mystic River. Do you think it would be possible for someone to sue the T you based on that? I mean, dozens of people had to escape through windows. At least one person jumped off of the bridge into the river.

Medwed: You know, that's a fascinating question. And I think the answer is yes, possibly. If someone could show that the T caused an injury and that it was due to negligence on the part of a T employee — maybe poor driving or a problem with the train or the track. My understanding is the T has indicated that they think the accident was caused when a metal sill, part of the undercarriage of a train, became dislodged and then made contact with the third rail of the track, and that ignited the fire. The question is, is that due to ordinary wear and tear, or is that due to carelessness, improper maintenance? We know that this train has been in service since January 1980. What's the maintenance record like over the last 42 years? So those are some of the key questions here that I think remain to be resolved.