The myths those fears of ISDS are based on are so widespread in Germany, that the EU commission felt the need to debunk them, by stating (among other things):

“ISDS is not about giving unlimited rights to multinationals to challenge any legislative measure taken by sovereign states in any area of regulation. Under TTIP, investors will not be compensated with taxpayers’ money just because of a fall in profits due to a change in the law. Nor will it be possible for investors to override bans of practices like fracking. The protection given covers a limited number of specific actions which can concretely affect an investor’s daily business operations in a foreign market, i.e. discrimination, denial of access to justice, expropriation without compensation and the inability to transfer capital to invest. Legitimate policy measures taken by public authorities to protect the environment or public health and which apply to all firms in the same way – foreign or national – cannot be successfully challenged under these provisions under the guise of investment protection.“

(from http://trade.ec.europa.eu/doclib/press/index.cfm?id=1008)