The Governor clearly has the power of the line-item veto, but that power is far from absolute. In fact, many of them might actually be illegal under the California Constitution, and a good claim could be made by somebody who is injured by the cuts.  First, here is the relevant section of the California Constitution, Art. IV, Sec. 10(e):

The Governor may reduce or eliminate one or more items of appropriation while approving other portions of a bill.  The Governor shall append to the bill a statement of the items reduced or eliminated with the reasons for the action.  The Governor shall transmit to the house originating the bill a copy of the statement and reasons.  Items reduced or eliminated shall be separately reconsidered and may be passed over the Governor’s veto in the same manner as bills.

Importantly, this is a budget revision, not a budget.  There weren’t any appropriations to the health and human services, only cuts in spending. The Legislature may cut funding for anything with a majority vote, and these majority vote changes to the budget do not allow for line item vetoes.  On something of a side note, the cuts are implemented immediately with a 2/3 vote, or in 90 days with a majority vote. Yes, this is a fantastic process, huh?

Either way, these cuts were not part of the budget. That was passed back in February.  A very strong argument could be made to the state courts that the line item veto isn’t applicable to these cuts in services. Take this from Senator Mark Leno:

We believe there are strong legal grounds to fight many of these vetoes. California’s constitution empowers the Governor to veto or reduce appropriations, but our budget agreement doesn’t make new appropriations, it makes spending reductions. In the end, my colleagues and I will fight these devastating cuts with everything we have.

There are all sorts of reasons as to why this isn’t really a budget that can be cut by the line item veto.  I won’t go into all of the details, but suffice it to say that this isn’t the last you’ve heard of the line-item veto.

Incidentally, the Legislature also has the power to override a veto.  It would involve the Legislators coming back for an override session, which hasn’t happened for over 25 years, but it certainly is high time that the Governor get a little pushback on this.