According to US law, if trademark 'ABC' has expired under 'Section 8/9' more than 10 years ago(2010), and has not seen any activity so far, can i trademark it?
After some research, you can IF:
The trademark is NOT used in trade, per example, if Apple failed to renew the trademark but is activelly using on products, they can always renew filling a new application.
The risk comes from the Lanham Act.
Through this act, a mark is not abandoned until it’s been discontinued without intent to resume use. While the USPTO will not track the mark in their registry as active because the paperwork has not been filed, this doesn’t mean that the mark isn’t still being used by a business who has an acceptable reason for not maintaining it in the registry.
If you can prove in court that the original owner had no intent to continue its use, then have at it. Understand, however, that the subjectivity of the process will give you problems if the previous owner pushes back.
2. The expired trademark is NOT in the 6-month grace period after expiration in wich, the original owner can renew.
I learned also that you could always ask(And is the best course of action), i spoke with some companies who had expired trademarks and they usually are willing grant the trademark, since the product/brand has been long dead.