Indeed, and LE had just that, and a whole lot more. They knew the perp was afoot, they followed a trail of blood drops. They knew he was wounded, losing lots of blood, and was seeking a place to hide. He was a specific and very big threat to anyone in the direction he was traveling afoot. Their biggest fear, he would find or commandeer a vehicle... hence a complete lockdown of all streets in a area around where the trail of blood led them - and their determination to thoroughly search every building within the parameters of where they thought he could be.
As it turned out - their perimeters were off - he was a block and a half outside those perimeters. They didn't find him - a homeowner did. It is that homeowner that deserves greater recognition than all the LEO's put together.
Read the law - they had legal warrant to do what they did. And yes, from what I saw, they did a pretty crappy job of it - but they were operating within the law, although in many instances far to broadly, imho.
If anyone wants to blow 150 million in lawsuits, or more, they might gain some pittance of monetary compensation years from now - that MA citizens would have to cough up.
No. Blood drops on my driveway, porch, boat, or threshold to my home are specific. A blood trail in the neighborhood is not. To lock down the area was permissible. To search homes with permission was permissible. Where was the urgent need to search a home over the objection of the homeowner, if any homeowners in Boston objected? They could have maintained their perimeter, requested a warrant for that specific address if they had probable cause, and searched lawfully. I don't know that anyone refused entry to the police and was searched anyways, but the point is the legal question of whether they have the right to search over such an objection. There is no precedent for a general search - none. Or do you have a specific case in mind in which the Supreme Court extended hot pursuit to also cover wide-ranging fishing expeditions?