Your questions

4H overcall?

CC wrote: We are playing duplicate. Both sides vulnerable

East is the dealer and opens 1S. South’s hand is H AK8652  D AK6 C KT95 and bids 4H. Is this a legitimate bid?

Rationale for the bid was East should have 13 or more points to open therefore North South probably can’t make a slam. Four Hearts is probably a good contract and why not bid it immediately and interfere with the opponents' bidding.

Derrick replied: Yes, bidding 4H could succeed in disrupting your opponents, but a better description would be to start with a double, planning to bid hearts next round to show a hand too strong to overcall.