HB 991 enforces comprehensive restrictions on abortion-related activities in Texas, criminalizing the distribution, mailing, or facilitation of access to abortion-inducing drugs. It establishes civil liabilities and provides a private right of action for individuals to sue those aiding or abetting abortion services. The bill mandates internet service providers to block access to online platforms promoting or facilitating abortion services. It extends the enforcement of Texas abortion laws extraterritorially to actions involving Texas residents outside the state. Additionally, it asserts immunity for state entities from lawsuits challenging these provisions and limits jurisdiction over such challenges within Texas courts.