Read it and weep

After all the blather about guns, the genuine problem is illustrated here.  That said, the ACLU's concern is a valid one. There is no simple answer to deciding what would be "enough evidence" to justify the state institutionalizing or medicating someone against his will, when he has not yet committed a crime. The obvious intermediate step would be a restraining order restricting the individuals's movements and prohibiting him from possessing or being in control any lethal weapon -- but in this case the shooter's own mother failed to do that and ended up dead herself.

As the initial shock and furor recedes, most people are going to recognize that there are no easy answers to be found. If there were, we'd have found them long before now.  A determined killer will sometimes find a way; all that can be done then is to minimize the damage by stopping him at the earliest possible moment. Step #1 should be to invoke plain common sense and recognize that mass shootings are being enabled by the folly of the "gun-free zones."